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/d3-scale-chromatic/src/sequential-single/Greens.js

@@ -0,0 +1,14 @@
+import colors from "../colors.js";
+import ramp from "../ramp.js";
+
+export var scheme = new Array(3).concat(
+  "e5f5e0a1d99b31a354",
+  "edf8e9bae4b374c476238b45",
+  "edf8e9bae4b374c47631a354006d2c",
+  "edf8e9c7e9c0a1d99b74c47631a354006d2c",
+  "edf8e9c7e9c0a1d99b74c47641ab5d238b45005a32",
+  "f7fcf5e5f5e0c7e9c0a1d99b74c47641ab5d238b45005a32",
+  "f7fcf5e5f5e0c7e9c0a1d99b74c47641ab5d238b45006d2c00441b"
+).map(colors);
+
+export default ramp(scheme);