feat(fase-7): collective-flow E2E coverage + fix 3 latent bugs

12 new Playwright tests closing the UI coverage gap in the collective
lifecycle (onboarding → invitation → admin manage). Writing them surfaced
three product-code bugs that have silently been present since Fase 1;
fixed as part of this phase.

Tests:
- tests/e2e/onboarding.test.ts       O-01..O-03 (Eva auto-redirect, happy
                                     path create, empty-name submit-disabled)
- tests/e2e/invitation.test.ts       I-01..I-05 (token generation, accept
                                     logged-out + logged-in, expired, used)
- tests/e2e/manage-collective.test.ts MC-02..MC-05 (promote, demote, remove
                                     member, generate pending invite)
- tests/fixtures/db.ts               resetEva, seedExpiredInvitation,
                                     seedUsedInvitation, restoreSeedMembership,
                                     countMembership — all via raw SQL so they
                                     don't depend on SUPABASE_SERVICE_ROLE_KEY

Bugs found & fixed:
- supabase/migrations/012_create_collective_rpc.sql: atomic
  `create_collective(name, emoji)` SECURITY DEFINER RPC. Fase 1 onboarding
  used `.insert(...).select().single()` which triggers the SELECT policy on
  the fresh row — creator isn't a member yet, so the INSERT was rejected with
  "row-level security" even though the INSERT policy passed. onboarding now
  calls the RPC which inserts both the collective AND the creator-as-admin
  membership in one transaction, bypassing RLS. F-08 in rls-isolation.test.ts
  has been silently masking this bug (only the spoof branch was asserted).

- routes/+layout.svelte: post-login redirect now reads sessionStorage
  `pendingInvitationToken` and routes back to /invitation/<token> instead of
  defaulting to /onboarding or /lists. The invitation page already stashed
  the token before kicking off Keycloak, but nothing read it back.

- routes/(app)/collective/manage/+page.svelte: loadMembers now subscribes
  to currentCollective so it re-runs when the store resolves after cold
  navigation. onMount alone races with the auth listener's first emit and
  the member list stayed empty on direct URL hits.

- routes/invitation/[token]/+page.svelte: awaits authLoading before deciding
  whether to redirect to login. Previously raced with the auth listener and
  triggered a redundant Keycloak round-trip for freshly-authenticated users.

Stable selectors added (Playwright):
- Onboarding: onboarding-create-tab, onboarding-join-tab,
  collective-name-input, collective-submit
- Manage: member-row-<uid>, role-select-<uid>, remove-member-<uid>,
  generate-invite, invite-link
- Invitation: invitation-accept, invitation-error (+ data-error-key attr)

Scope dropped from the plan — UI does not exist, would be feature work:
- O-04: "+ new collective" affordance in the sidebar.
- MC-01: rename-collective input in /collective/manage.
Both flagged as follow-ups in plan/fase-7-collective-flow-tests.md.

Test totals: 34 pgTAP + 140 Vitest integration + 15 Vitest unit + 58
Playwright + 1 gated rate-limit. 3 skipped (2 Realtime presence, 1 gated).

apps/web/tests/fixtures/db.ts

@@ -0,0 +1,110 @@
+/**
+ * DB helpers for Fase 7 E2E tests — direct-to-postgres helpers that bypass RLS
+ * via the admin client. Import from `*.test.ts` only, never from `src/`.
+ *
+ * These helpers exist because Fase 7 exercises collective creation end-to-end:
+ * tests need to reset the "Eva has no collective" precondition between runs
+ * and seed invitation rows in exotic states (expired / already-accepted) that
+ * the UI can't produce on its own.
+ */
+import { sql, ANA_ID, COLLECTIVE_ID } from '@colectivo/test-utils';
+
+/**
+ * Scrub all state created by Eva and all memberships she holds.
+ *
+ * Call in `beforeEach` of suites that assume Eva is a non-member at start.
+ * Implementation via raw SQL (bypasses RLS + cascades) instead of admin client
+ * to avoid a two-step delete dance.
+ */
+export async function resetEva(): Promise<void> {
+	const EVA_ID = '55555555-5555-5555-5555-555555555555';
+	// Delete collectives Eva created (CASCADE wipes members + invitations + lists).
+	await sql('DELETE FROM public.collectives WHERE created_by = $1', [EVA_ID]);
+	// Clear any memberships Eva holds in other collectives.
+	await sql('DELETE FROM public.collective_members WHERE user_id = $1', [EVA_ID]);
+	// Clear any invitations that *targeted* Eva (accepted_by).
+	await sql(
+		'UPDATE public.collective_invitations SET accepted_at = NULL, accepted_by = NULL WHERE accepted_by = $1',
+		[EVA_ID]
+	);
+}
+
+/**
+ * Insert an invitation row with an expires_at in the past.
+ * Returns the token (uuid).
+ */
+export async function seedExpiredInvitation(
+	collectiveId: string = COLLECTIVE_ID,
+	createdBy: string = ANA_ID
+): Promise<string> {
+	const res = await sql(
+		`INSERT INTO public.collective_invitations (collective_id, role, created_by, expires_at)
+		 VALUES ($1, 'member', $2, now() - interval '1 hour')
+		 RETURNING token`,
+		[collectiveId, createdBy]
+	);
+	return res.rows[0].token as string;
+}
+
+/**
+ * Insert an invitation row already marked accepted (accepted_at + accepted_by).
+ * Returns the token.
+ */
+export async function seedUsedInvitation(
+	collectiveId: string = COLLECTIVE_ID,
+	createdBy: string = ANA_ID,
+	acceptedBy: string = ANA_ID
+): Promise<string> {
+	const res = await sql(
+		`INSERT INTO public.collective_invitations (collective_id, role, created_by, accepted_at, accepted_by)
+		 VALUES ($1, 'member', $2, now(), $3)
+		 RETURNING token`,
+		[collectiveId, createdBy, acceptedBy]
+	);
+	return res.rows[0].token as string;
+}
+
+/**
+ * Reset the seed collective's membership roster back to the post-seed state:
+ *   Ana = admin, Borja = member, Carmen = member, David = guest
+ *
+ * Call in `afterAll` of suites that mutate roles / remove members. Critical —
+ * downstream suites (lists, items, tasks, notes) assume this shape.
+ */
+export async function restoreSeedMembership(): Promise<void> {
+	// Use raw SQL to bypass RLS without needing the service-role JWT (which
+	// isn't always exported to the Playwright process env).
+	const seed = [
+		['11111111-1111-1111-1111-111111111111', 'admin'],
+		['22222222-2222-2222-2222-222222222222', 'member'],
+		['33333333-3333-3333-3333-333333333333', 'member'],
+		['44444444-4444-4444-4444-444444444444', 'guest']
+	] as const;
+
+	for (const [userId, role] of seed) {
+		await sql(
+			`INSERT INTO public.collective_members (collective_id, user_id, role)
+			 VALUES ($1, $2, $3::public.member_role)
+			 ON CONFLICT (collective_id, user_id) DO UPDATE SET role = EXCLUDED.role`,
+			[COLLECTIVE_ID, userId, role]
+		);
+	}
+
+	// Rename the collective back if a test changed it. Emoji stays whatever.
+	await sql('UPDATE public.collectives SET name = $1 WHERE id = $2', [
+		'Casa García-López',
+		COLLECTIVE_ID
+	]);
+
+	// Nuke any invitations that accumulated.
+	await sql('DELETE FROM public.collective_invitations WHERE collective_id = $1', [COLLECTIVE_ID]);
+}
+
+/** Count rows in collective_members for a given (collective, user). 0 or 1. */
+export async function countMembership(collectiveId: string, userId: string): Promise<number> {
+	const res = await sql(
+		'SELECT count(*)::int AS n FROM public.collective_members WHERE collective_id = $1 AND user_id = $2',
+		[collectiveId, userId]
+	);
+	return res.rows[0].n as number;
+}