feat(ui): project drill-down route with repo-filtered event timeline

Add repo filter param to /v1/events (SQL COALESCE across payload
shapes per source). New /project/:source/* route renders a filtered
activity timeline for a single repo. Dashboard cards link to the
drill-down page.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ui/src/App.tsx

@@ -8,6 +8,7 @@ import './App.css';
 import { Layout } from './components/Layout';
 import { DashPage } from './pages/DashPage';
 import { TimelineHome } from './pages/TimelineHome';
+import { ProjectPage } from './pages/ProjectPage';
 import { CvPage } from './pages/CvPage';
 
 export default function App() {
@@ -17,6 +18,7 @@ export default function App() {
         <Route index element={<DashPage />} />
         <Route path="/dash" element={<DashPage />} />
         <Route path="/activity" element={<TimelineHome />} />
+        <Route path="/project/:source/*" element={<ProjectPage />} />
         <Route path="/cv" element={<CvPage />} />
       </Route>
     </Routes>