ui_design v2: redesign of all 5 pages

ui_design v2: tactical-ops redesign of all 5 pages

Two parallel takes on visual polish for flights, annotations, dataset
explorer, admin, and settings.

- v2/plugin/ — self-contained HTML produced via the frontend-design
  plugin, adheres to v2/plugin/_design_system.md..
- v2/stitch/ — Google Stitch MCP exports against the same design
  system.

IA from the original wireframes in _docs/ui_design/ is preserved
verbatim — this pass is visual only.

src/auth/AuthContext.tsx

@@ -16,22 +16,6 @@ export function useAuth() {
   return useContext(AuthContext)
 }
 
-// React 18+ StrictMode double-invokes effects in dev (mount → cleanup → mount),
-// and the backend rotates the refresh cookie on every successful POST. Two
-// concurrent bootstraps would race the rotation and leave the second one with
-// a stale cookie. The module-scoped in-flight promise lets the second mount
-// await the first's network round-trip instead of duplicating it. Risk 4 in
-// AZ-510 spec.
-let bootstrapInflight: Promise<AuthUser | null> | null = null
-
-/**
- * Test-only hook to clear the module-scoped in-flight bootstrap promise
- * between Vitest tests. Production never imports this — it exists because
- * Vitest does not reset module state between tests, so a test that mocks the
- * bootstrap to never-resolve would otherwise leak a permanently-pending
- * promise that subsequent tests would await forever. Wired into
- * `tests/setup.ts` afterEach. Safe-no-op when nothing is in flight.
- */
 export function __resetBootstrapInflightForTests(): void {
   bootstrapInflight = null
 }