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/lodash-es/_Stack.js

@@ -0,0 +1,27 @@
+import ListCache from './_ListCache.js';
+import stackClear from './_stackClear.js';
+import stackDelete from './_stackDelete.js';
+import stackGet from './_stackGet.js';
+import stackHas from './_stackHas.js';
+import stackSet from './_stackSet.js';
+
+/**
+ * Creates a stack cache object to store key-value pairs.
+ *
+ * @private
+ * @constructor
+ * @param {Array} [entries] The key-value pairs to cache.
+ */
+function Stack(entries) {
+  var data = this.__data__ = new ListCache(entries);
+  this.size = data.size;
+}
+
+// Add methods to `Stack`.
+Stack.prototype.clear = stackClear;
+Stack.prototype['delete'] = stackDelete;
+Stack.prototype.get = stackGet;
+Stack.prototype.has = stackHas;
+Stack.prototype.set = stackSet;
+
+export default Stack;