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/preact/compat/client.mjs

@@ -0,0 +1,24 @@
+import { render, hydrate, unmountComponentAtNode } from 'preact/compat';
+
+export function createRoot(container) {
+	return {
+		// eslint-disable-next-line
+		render: function (children) {
+			render(children, container);
+		},
+		// eslint-disable-next-line
+		unmount: function () {
+			unmountComponentAtNode(container);
+		}
+	};
+}
+
+export function hydrateRoot(container, children) {
+	hydrate(children, container);
+	return createRoot(container);
+}
+
+export default {
+	createRoot,
+	hydrateRoot
+};