feat(web): wire dashboard widgets to real API data (#459)

- Create dashboard API client with TypeScript interfaces
- Update page.tsx to fetch from GET /api/dashboard/summary on mount
- DashboardMetrics: accept metrics prop, map to 6 cells with real data
- ActivityFeed: accept items prop, map actions to icons/timestamps
- OrchestratorSessions: accept jobs prop, render steps as agent nodes
- TokenBudget: accept budgets prop, compute percentages
- All widgets have empty/zero fallback states
- Update page tests to mock API fetch

Task: MS-P2-002

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

apps/web/src/lib/api/index.ts

@@ -13,3 +13,4 @@ export * from "./domains";
 export * from "./teams";
 export * from "./personalities";
 export * from "./telemetry";
+export * from "./dashboard";