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/components/auth/auth-shell.tsx

@@ -0,0 +1,33 @@
+import { type ReactNode } from "react"
+
+import { useBrand } from "~/lib/identity"
+
+export function AuthShell({ children }: { children: ReactNode }) {
+  return (
+    <div
+      className="dark relative isolate flex min-h-svh items-center justify-center p-4"
+      style={{ background: "var(--background)" }}
+    >
+      {children}
+    </div>
+  )
+}
+
+export function AuthBrand() {
+  const brand = useBrand()
+  const BrandIcon = brand.icon
+  return (
+    <div className="flex items-center gap-2">
+      <span
+        className="flex size-8 items-center justify-center rounded-lg"
+        style={{
+          background: "var(--primary)",
+          color: "var(--primary-foreground)",
+        }}
+      >
+        <BrandIcon className="size-4" />
+      </span>
+      <span className="text-sm font-semibold">{brand.name}</span>
+    </div>
+  )
+}