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/index-array-by/dist/index-array-by.d.ts

@@ -0,0 +1,23 @@
+type ListItem = any;
+
+type KeyAccessor = string | ((listItem: ListItem) => string);
+
+type ReducerFn = (items: ListItem[]) => any;
+
+interface NestedResult {
+  [key: string]: NestedResult | ListItem | ListItem[];
+}
+
+type FlatResult = {
+  keys: string[];
+  vals: ListItem | ListItem[]
+}[];
+
+declare function indexBy(
+  list: ListItem[],
+  keyAccessors: KeyAccessor | KeyAccessor[],
+  multiItem?: boolean | ReducerFn,
+  flattenKeys?: boolean
+): NestedResult | FlatResult;
+
+export { indexBy as default };