feat(#52): implement Active Projects & Agent Chains widget

Add HUD widget for tracking active projects and running agent sessions.

Backend:
- Add getActiveProjectsData() and getAgentChainsData() to WidgetDataService
- Create POST /api/widgets/data/active-projects endpoint
- Create POST /api/widgets/data/agent-chains endpoint
- Add WidgetProjectItem and WidgetAgentSessionItem response types

Frontend:
- Create ActiveProjectsWidget component with dual panels
- Active Projects panel: name, color, task/event counts, last activity
- Agent Chains panel: status, runtime, message count, expandable details
- Real-time updates (projects: 30s, agents: 10s)
- PDA-friendly status indicators (Running vs URGENT)

Testing:
- 7 comprehensive tests covering loading, rendering, empty states, expandability
- All tests passing (7/7)

Refs #52

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

apps/api/src/widgets/widgets.controller.ts

@@ -100,4 +100,30 @@ export class WidgetsController {
     }
     return this.widgetDataService.getCalendarPreviewData(workspaceId, query);
   }
+
+  /**
+   * POST /api/widgets/data/active-projects
+   * Get active projects widget data
+   */
+  @Post("data/active-projects")
+  async getActiveProjectsData(@Request() req: AuthenticatedRequest) {
+    const workspaceId = req.user?.currentWorkspaceId ?? req.user?.workspaceId;
+    if (!workspaceId) {
+      throw new UnauthorizedException("Workspace ID required");
+    }
+    return this.widgetDataService.getActiveProjectsData(workspaceId);
+  }
+
+  /**
+   * POST /api/widgets/data/agent-chains
+   * Get agent chains widget data (active agent sessions)
+   */
+  @Post("data/agent-chains")
+  async getAgentChainsData(@Request() req: AuthenticatedRequest) {
+    const workspaceId = req.user?.currentWorkspaceId ?? req.user?.workspaceId;
+    if (!workspaceId) {
+      throw new UnauthorizedException("Workspace ID required");
+    }
+    return this.widgetDataService.getAgentChainsData(workspaceId);
+  }
 }