feat(fase-10): CU-H06 leave collective — RPC + settings UI

Migration 017 adds public.leave_collective(uuid) with three branches:
- normal member: remove membership row
- sole admin with other members: promote oldest-joined remaining member
  to admin (inline; the existing user-delete trigger does not cover the
  membership-delete path), then remove the row
- sole member: reject with errcode P0001 so the UI can direct the user
  to the dissolve flow (CU-H08)

Settings page gains a "Your collectives" section listing the user's
memberships with a per-row Leave button; the confirmation modal calls
the RPC, drops the collective from local stores, and either switches
to the next collective or sends the user to /onboarding when none
remain. Also seeds the Danger zone scaffolding for Fase 10.5 and adds
all message keys consumed by 10.1, 10.3, 10.5 and 10.6.

pgTAP 010 (7 assertions): member-leave, sole-admin-leave + auto-promote,
sole-member rejected with P0001. Playwright L-01 walks Borja through
the UI flow + checks the seed collective survives (content stays).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

apps/web/src/routes/(app)/settings/+page.svelte

@@ -1,7 +1,9 @@
 <script lang="ts">
 	import { onMount } from 'svelte';
+	import { goto } from '$app/navigation';
 	import { getSupabase } from '$lib/supabase';
 	import { currentUser } from '$lib/stores/auth';
+	import { userCollectives, currentCollective } from '$lib/stores/collective';
 	import { logout } from '$lib/auth';
 	import Avatar from '$lib/components/Avatar.svelte';
 	import ImageCropper from '$lib/components/ImageCropper.svelte';
@@ -156,6 +158,93 @@
 			.update({ language: lang })
 			.eq('id', $currentUser!.id);
 	}
+
+	// ── Fase 10.1: leave collective (CU-H06) ────────────────────────────────
+	let leaveCandidate = $state<{ id: string; name: string } | null>(null);
+	let leaveError = $state<string | null>(null);
+
+	function startLeave(c: { id: string; name: string }) {
+		leaveCandidate = c;
+		leaveError = null;
+	}
+
+	function cancelLeave() {
+		leaveCandidate = null;
+		leaveError = null;
+	}
+
+	async function confirmLeave() {
+		if (!leaveCandidate) return;
+		const target = leaveCandidate;
+		const supabase = getSupabase();
+		const { error } = await supabase.rpc('leave_collective', { p_collective_id: target.id });
+		if (error) {
+			// P0001 = sole member → instruct to dissolve instead.
+			leaveError = (error as { code?: string }).code === 'P0001'
+				? m.settings_collectives_dissolve_hint()
+				: error.message;
+			return;
+		}
+
+		// Update local stores: drop the collective from userCollectives. If it
+		// was the active one, switch to the next or kick to /onboarding.
+		const remaining = $userCollectives.filter((c) => c.id !== target.id);
+		userCollectives.set(remaining);
+
+		if ($currentCollective?.id === target.id) {
+			if (remaining.length > 0) {
+				const next = remaining[0];
+				currentCollective.set(next);
+				localStorage.setItem('activeCollectiveId', next.id);
+			} else {
+				currentCollective.set(null);
+				localStorage.removeItem('activeCollectiveId');
+				leaveCandidate = null;
+				await goto('/onboarding');
+				return;
+			}
+		}
+
+		leaveCandidate = null;
+	}
+
+	// ── Fase 10.5: delete account ───────────────────────────────────────────
+	let showDeleteAccount = $state(false);
+	let deleteConfirmInput = $state('');
+	let deleteAccountError = $state<string | null>(null);
+	let deleteInFlight = $state(false);
+
+	const deleteConfirmWord = m.settings_delete_account_confirm_word();
+	const deleteConfirmReady = $derived(deleteConfirmInput === deleteConfirmWord);
+
+	function openDeleteAccount() {
+		showDeleteAccount = true;
+		deleteConfirmInput = '';
+		deleteAccountError = null;
+	}
+
+	function closeDeleteAccount() {
+		showDeleteAccount = false;
+		deleteConfirmInput = '';
+		deleteAccountError = null;
+	}
+
+	async function confirmDeleteAccount() {
+		if (!deleteConfirmReady || deleteInFlight) return;
+		deleteInFlight = true;
+		deleteAccountError = null;
+		const { error } = await getSupabase().rpc('delete_account');
+		if (error) {
+			deleteInFlight = false;
+			deleteAccountError = (error as { code?: string }).code === 'P0003'
+				? m.settings_delete_account_blocked()
+				: error.message;
+			return;
+		}
+		// GoTrue row gone; clear local + start logout (RP-initiated) so Keycloak
+		// session is also ended. /logged-out is the post-logout landing.
+		await logout();
+	}
 </script>
 
 <div class="flex flex-1 flex-col overflow-hidden">
@@ -280,6 +369,34 @@
 			     import.meta.env.DEV inside the component itself. -->
 			<SyncConflictsPanel />
 
+			<!-- Collectives (Fase 10.1) -->
+			<section>
+				<p class="mb-3 text-[13px] font-semibold uppercase tracking-[0.05em] text-text-secondary">
+					{m.settings_collectives()}
+				</p>
+				{#if $userCollectives.length === 0}
+					<p class="text-sm text-text-secondary">{m.settings_collectives_empty()}</p>
+				{:else}
+					<ul>
+						{#each $userCollectives as c (c.id)}
+							<li data-testid="collective-row-{c.id}" class="flex items-center gap-3 py-2">
+								<span class="text-lg">{c.emoji}</span>
+								<span class="min-w-0 flex-1 truncate text-sm text-slate-900 dark:text-slate-50">{c.name}</span>
+								<button
+									type="button"
+									data-testid="leave-collective-{c.id}"
+									onclick={() => startLeave(c)}
+									class="rounded-md border border-slate-300 px-3 py-1 text-xs font-medium text-slate-700
+										hover:bg-slate-50 dark:border-slate-600 dark:text-slate-300 dark:hover:bg-slate-800"
+								>
+									{m.settings_collectives_leave()}
+								</button>
+							</li>
+						{/each}
+					</ul>
+				{/if}
+			</section>
+
 			<!-- Account — spacing creates the separation, not a border line -->
 			<section class="pt-8">
 				<p class="mb-3 text-[13px] font-semibold uppercase tracking-[0.05em] text-text-secondary">
@@ -300,6 +417,23 @@
 					{m.settings_logout()}
 				</button>
 			</section>
+
+			<!-- Danger zone (Fase 10.5) -->
+			<section class="pt-8">
+				<p class="mb-3 text-[13px] font-semibold uppercase tracking-[0.05em] text-destructive">
+					{m.settings_danger_zone()}
+				</p>
+				<p class="mb-3 text-sm text-text-secondary">{m.settings_delete_account_blurb()}</p>
+				<button
+					type="button"
+					data-testid="delete-account-open"
+					onclick={openDeleteAccount}
+					class="rounded-md border border-destructive px-4 py-2 text-sm font-semibold text-destructive
+						hover:bg-destructive/10"
+				>
+					{m.settings_delete_account()}
+				</button>
+			</section>
 		</div>
 	</div>
 </div>
@@ -311,3 +445,79 @@
 		onCancel={() => (cropperFile = null)}
 	/>
 {/if}
+
+<!-- Leave-collective confirmation modal (Fase 10.1) -->
+{#if leaveCandidate}
+	<div class="fixed inset-0 z-50 flex items-center justify-center bg-black/40 p-4" data-testid="leave-modal">
+		<div class="w-full max-w-sm rounded-lg bg-surface p-5 shadow-[0px_20px_40px_rgba(15,23,42,0.2)] dark:bg-surface-raised">
+			<h2 class="mb-2 text-base font-semibold text-slate-900 dark:text-slate-50">
+				{m.settings_collectives_confirm_leave_title({ name: leaveCandidate.name })}
+			</h2>
+			<p class="mb-4 text-sm text-text-secondary">{m.settings_collectives_confirm_leave_body()}</p>
+			{#if leaveError}
+				<p class="mb-3 text-sm text-destructive" data-testid="leave-error">{leaveError}</p>
+			{/if}
+			<div class="flex justify-end gap-2">
+				<button
+					type="button"
+					onclick={cancelLeave}
+					class="rounded-md px-3 py-1.5 text-sm font-medium text-slate-600 hover:bg-slate-100 dark:text-slate-300 dark:hover:bg-slate-800"
+				>
+					{m.common_cancel()}
+				</button>
+				<button
+					type="button"
+					data-testid="confirm-leave-collective"
+					onclick={confirmLeave}
+					class="rounded-md bg-destructive px-4 py-1.5 text-sm font-semibold text-white hover:opacity-90"
+				>
+					{m.settings_collectives_confirm_leave_button()}
+				</button>
+			</div>
+		</div>
+	</div>
+{/if}
+
+<!-- Delete-account modal (Fase 10.5) -->
+{#if showDeleteAccount}
+	<div class="fixed inset-0 z-50 flex items-center justify-center bg-black/40 p-4" data-testid="delete-account-modal">
+		<div class="w-full max-w-md rounded-lg bg-surface p-5 shadow-[0px_20px_40px_rgba(15,23,42,0.2)] dark:bg-surface-raised">
+			<h2 class="mb-2 text-base font-semibold text-slate-900 dark:text-slate-50">
+				{m.settings_delete_account_modal_title()}
+			</h2>
+			<p class="mb-4 text-sm text-text-secondary">{m.settings_delete_account_modal_body()}</p>
+			<label for="delete-account-input" class="mb-1 block text-xs font-medium text-text-secondary">
+				{m.settings_delete_account_confirm_label({ word: deleteConfirmWord })}
+			</label>
+			<input
+				id="delete-account-input"
+				data-testid="delete-account-confirm-input"
+				type="text"
+				bind:value={deleteConfirmInput}
+				class="mb-3 w-full rounded-lg border border-slate-300 bg-surface px-3 py-2 text-sm
+					focus:border-slate-500 focus:outline-none dark:border-slate-600 dark:bg-slate-800"
+			/>
+			{#if deleteAccountError}
+				<p class="mb-3 text-sm text-destructive" data-testid="delete-account-error">{deleteAccountError}</p>
+			{/if}
+			<div class="flex justify-end gap-2">
+				<button
+					type="button"
+					onclick={closeDeleteAccount}
+					class="rounded-md px-3 py-1.5 text-sm font-medium text-slate-600 hover:bg-slate-100 dark:text-slate-300 dark:hover:bg-slate-800"
+				>
+					{m.common_cancel()}
+				</button>
+				<button
+					type="button"
+					data-testid="confirm-delete-account"
+					disabled={!deleteConfirmReady || deleteInFlight}
+					onclick={confirmDeleteAccount}
+					class="rounded-md bg-destructive px-4 py-1.5 text-sm font-semibold text-white hover:opacity-90 disabled:opacity-50"
+				>
+					{m.settings_delete_account_button()}
+				</button>
+			</div>
+		</div>
+	</div>
+{/if}