Add side panels, task selection, graph animation, and project docs

- Foldable left panel (user profile) and right panel (task details)
- Clicking a task in the list or graph node selects it and shows details
- Both views (task list + graph) always mounted via absolute inset-0 for
  correct canvas dimensions; tabs toggle visibility with opacity
- Graph node selection animation: other nodes repel outward (charge -600),
  then selected node smoothly slides to center (500ms cubic ease-out),
  then charge restores to -120 and graph stabilizes
- Graph re-fits on tab switch and panel resize via ResizeObserver
- Fix UUID string IDs throughout (backend returns UUIDs, not integers)
- Add TaskDetailPanel, UserPanel components
- Add CLAUDE.md project documentation

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

frontend/node_modules/next/dist/lib/memory/gc-observer.d.ts

@@ -0,0 +1,12 @@
+/**
+ * Starts recording garbage collection events in the process and warn on long
+ * running GCs. To disable, call `stopObservingGc`.
+ */
+export declare function startObservingGc(): void;
+export declare function stopObservingGc(): void;
+/**
+ * Returns all recorded garbage collection events. This function will only
+ * return information from when `startObservingGc` was enabled and before
+ * `stopObservingGc` was called.
+ */
+export declare function getGcEvents(): PerformanceEntry[];