admin: completeness + UI consistency pass

Arcadia wiring:
- home: real Overview dashboard (tenants/users/audit/health probe) replacing the inherited Vibespace welcome tiles; skeleton loaders, refresh button, registers admin context
- profile: split into Account (synced via getUser/updateUser of session user) and local Preferences; updateSessionUser keeps the appbar in sync after edits
- session: drop unused signIn mock, add updateSessionUser, refresh tests
- profile schema: drop redundant Profile.name/email (session is the source of truth)
- routes: delete orphaned resources route + lib

Auth flows that previously 404'd:
- /signup, /login/forgot, /login/reset, /login/2fa wired via @crema/arcadia-auth-ui
- shared AuthShell + AuthBrand wrapper

Assistant tools (admin-tools.ts):
- +10 tools: deactivate_tenant, set_user_status, delete_user, list_memberships, list_roles, revoke_api_key, create_user, update_user, assign_role, remove_role
- list_memberships gains user_id filter for "tenants this user belongs to" queries
- search_kb / read_chunk: new token resolution (window override → VITE_ARCADIA_SEARCH_TOKEN service token → operator session JWT → "dev"); on 401/403 emit a tailored hint based on which token was used

UI consistency:
- new PageHeader component
- AppShell.title was unrendered — dropped; first-child padding on #main-content keeps the floating actions pill from colliding with header content
- removed dead "Sign in required" fallback cards from 14 routes (AppShell already redirects)
- stripped p-6 from outer wrappers across 14 routes (was double-padding under AppShell's own p-6)
- migrated home + tenants to PageHeader

arcadia-search ergonomics:
- scripts/mint-search-token.mjs + `npm run mint:search-token` mints HS512 JWT with required tenant_id claim, upserts VITE_ARCADIA_SEARCH_TOKEN into .env.local
- README/.env document the new VITE_ARCADIA_SEARCH_URL / VITE_ARCADIA_SEARCH_TOKEN knobs
- .env.local now gitignored

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

app/routes/users.tsx

@@ -169,29 +169,9 @@ export default function UsersRoute() {
   )
   useRegisterAdminContext("users", summary)
 
-  if (!session) {
-    return (
-      <AppShell title="Users">
-        <div className="p-8">
-          <Card className="max-w-md">
-            <CardHeader>
-              <CardTitle>Sign in required</CardTitle>
-              <CardDescription>User administration requires an admin session.</CardDescription>
-            </CardHeader>
-            <CardContent>
-              <Button asChild>
-                <Link to="/login?next=/users">Sign in</Link>
-              </Button>
-            </CardContent>
-          </Card>
-        </div>
-      </AppShell>
-    )
-  }
-
   return (
-    <AppShell title="Users">
-      <div className="flex flex-col gap-4 p-6">
+    <AppShell>
+      <div className="flex flex-col gap-4">
         <header className="flex flex-col gap-2">
           <h1 className="text-2xl font-semibold tracking-tight">Users</h1>
           <p className="text-sm text-muted-foreground">