feat(phase-2): workstream 6 — Web Dashboard UI

- dashboard/: Vite 5 + React 18 + TypeScript strict SPA
  - Auth: sessionStorage credentials, TokenManager validation, AuthProvider context
  - Pages: Login, Agents (search + filter), AgentDetail (suspend/reactivate),
    Credentials (generate/rotate/revoke, new secret shown once),
    AuditLog (filters + pagination), Health (PG + Redis status, 30s refresh)
  - Components: Button, Badge, ConfirmDialog, AppShell, RequireAuth
  - All destructive actions gated by ConfirmDialog
  - Zero dangerouslySetInnerHTML; sessionStorage only (OWASP compliant)
- src/routes/health.ts: unauthenticated GET /health — PG + Redis connectivity
- src/app.ts: health route + dashboard/dist/ served at /dashboard with SPA fallback
- 6 new health route tests; 308/308 unit tests passing

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

dashboard/src/index.css

@@ -0,0 +1,26 @@
+@tailwind base;
+@tailwind components;
+@tailwind utilities;
+
+@layer base {
+  :root {
+    --background: 0 0% 100%;
+    --foreground: 222.2 84% 4.9%;
+    --muted: 210 40% 96.1%;
+    --muted-foreground: 215.4 16.3% 46.9%;
+    --border: 214.3 31.8% 91.4%;
+    --input: 214.3 31.8% 91.4%;
+    --ring: 198 89% 48%;
+    --radius: 0.5rem;
+  }
+}
+
+* {
+  box-sizing: border-box;
+}
+
+body {
+  font-family: system-ui, -apple-system, sans-serif;
+  background-color: #f8fafc;
+  color: #0f172a;
+}