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>

CLAUDE.md

@@ -0,0 +1,86 @@
+# Taskpile
+
+A task manager with force-directed graph visualization.
+
+## Architecture
+
+- **Frontend**: Next.js 14 (App Router) + React 18 + Tailwind CSS 3 + TypeScript
+- **Backend**: Rust (Axum 0.7) + SQLite (via SQLx)
+- **Graph**: `react-force-graph-2d` for force-directed visualization
+
+## Project Structure
+
+```
+frontend/
+  src/app/page.tsx          — Main page: tabs, panels, task state management
+  src/app/layout.tsx        — Root layout
+  src/components/
+    GraphView.tsx            — Force graph with node selection, drag-to-center
+    TaskList.tsx             — Pending/completed task list with selection
+    TaskItem.tsx             — Individual task card
+    AddTaskForm.tsx          — New task form
+    TaskDetailPanel.tsx      — Right panel: selected task details
+    UserPanel.tsx            — Left panel: user profile (example data)
+    ForceGraphClient.tsx     — ForceGraph2D ref wrapper for dynamic import
+  src/lib/
+    api.ts                   — API client (fetch wrappers)
+    types.ts                 — TypeScript interfaces
+  src/__tests__/
+    unit/                    — Jest unit tests (API, TaskItem)
+    e2e/                     — Jest integration tests (full user flows)
+
+backend/
+  src/main.rs               — Axum server on port 3001
+  src/models.rs             — Task, GraphNode, GraphEdge structs
+  src/db.rs                 — SQLite pool + migrations
+  src/graph.rs              — Deterministic edge generation (~30% pairs)
+  src/routes/tasks.rs       — CRUD: GET/POST /api/tasks, PATCH/DELETE /api/tasks/:id
+  src/routes/graph.rs       — GET /api/graph
+  tests/integration_test.rs — Axum integration tests
+```
+
+## Running
+
+```bash
+# Backend (port 3001)
+cd backend && cargo run
+
+# Frontend (port 3003, proxies /api to backend)
+cd frontend && npm run dev -- -p 3003
+```
+
+Port 3000 is used by Gitea on this machine — use 3003 for the frontend.
+
+## Testing
+
+```bash
+# Frontend tests
+cd frontend && npx jest
+
+# Backend tests
+cd backend && cargo test
+```
+
+## Key Design Decisions
+
+- Task IDs are UUIDs (TEXT in SQLite, string from backend). Frontend `Task.id` is typed as `number` but actually receives strings — selection uses string comparison throughout.
+- Graph tab and task list are switched via tabs in the center area. Left panel (user info) and right panel (task details) are independently foldable.
+- Selecting a task (from list or graph node click) animates the node to the center of the viewport (drag-style, not camera pan). The node stays pinned until a different task is selected.
+- `ForceGraph2D` canvas dimensions are driven by a `ResizeObserver` on a container div that always renders. The canvas is only mounted after the first measurement to avoid a 300x300 default.
+- Panel transitions are 300ms CSS; graph re-fit/re-center delays 350ms to wait for the transition.
+
+## API
+
+All endpoints under `/api`:
+
+| Method | Path | Description |
+|--------|------|-------------|
+| GET | /tasks | List all tasks |
+| POST | /tasks | Create task `{title, description?}` |
+| PATCH | /tasks/:id | Update task `{title?, description?, completed?}` |
+| DELETE | /tasks/:id | Delete task |
+| GET | /graph | Get nodes + weighted edges |
+
+## Proxy
+
+Do not use system proxy env vars when testing the app locally — `curl --noproxy '*'` or equivalent.