feat(fase-13): admin UI + sidebar entry + isServerAdmin store + e2e SA-01..04

13.3 admin UI:
  - (admin) route group with own layout + red banner + sidebar (Collectives,
    Admins, Audit log, Server). +layout.ts is client-rendered (ssr=false),
    same rationale as the (app) group.
  - /admin/collectives — paginated list via admin_list_collectives, search
    by name, soft-delete / restore / hard-delete modals (hard-delete needs
    explicit checkbox; force toggle bypasses the 30-day wait server-side).
  - /admin/collectives/[id] — members list with kick action; recent actions
    for the collective filtered from admin_actions.
  - /admin/admins — list via server_admins join to users (disambiguated by
    FK name — there are TWO FKs to users so the embed needs the explicit
    server_admins_user_id_fkey); promote modal does an email lookup; revoke
    button is replaced by "you (cannot revoke yourself while sole admin)"
    when applicable.
  - /admin/audit — paginated feed (default 50), action filter.
  - /admin/server — server-layer default-section toggles backed by
    admin_set_default_section + the new admin_clear_default_section RPC
    (added because patching the JSONB to `true` is NOT equivalent to "no
    opinion" — `true` explicitly overrides a collective OFF).

13.4 sidebar/drawer entry:
  - $isServerAdmin store (writable; +$isServerAdminLoaded for the gate
    race) refreshed on every onAuthStateChange in root layout, cleared on
    sign-out. Cached so the sidebar tile is synchronous.
  - DesktopSidebar + MobileDrawer render the entry only when the store is
    true. Distinct red icon so it never blends with normal nav.

Stores wiring:
  - features.ts gains serverSectionDefaults writable + enabledSections
    derived now reads server > collective > user > default. Loader
    piggybacks on loadCurrentUserFeatures so the server layer is fetched
    once per sign-in.
  - serverAdmin.ts new module — refreshServerAdminFlag() + clearServerAdminFlag().
  - Tracks isServerAdminLoaded so the (admin) layout doesn't redirect away
    during the millisecond between SIGNED_IN and the RPC resolving (caught
    empirically — every hard-load to /admin/* bounced to / without it).

13.5 tests:
  - admin.test.ts (SA-01..SA-04) with new loginAsAdmin fixture. Ana is the
    seed admin (server_admins seeded via supabase/seed.sql).
  - SA-04 + SV-02 reset their server-layer JSONB via the new
    admin_clear_default_section RPC so the suites don't leak state into
    each other.

Migration 025 adds admin_clear_default_section(text) — same SECURITY DEFINER
+ audit pattern as the rest. pgTAP 017 updated (23 plans, AR-T13b + the
SECURITY DEFINER list now includes the clear RPC).

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

packages/types/src/database.ts

@@ -614,6 +614,10 @@ export interface Database {
 				Args: { p_section: string; p_enabled: boolean };
 				Returns: void;
 			};
+			admin_clear_default_section: {
+				Args: { p_section: string };
+				Returns: void;
+			};
 		};
 		Enums: {
 			language_code: LanguageCode;