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/autoprefixer/lib/hacks/file-selector-button.js

@@ -0,0 +1,26 @@
+let Selector = require('../selector')
+let utils = require('../utils')
+
+class FileSelectorButton extends Selector {
+  constructor(name, prefixes, all) {
+    super(name, prefixes, all)
+
+    if (this.prefixes) {
+      this.prefixes = utils.uniq(this.prefixes.map(() => '-webkit-'))
+    }
+  }
+
+  /**
+   * Return different selectors depend on prefix
+   */
+  prefixed(prefix) {
+    if (prefix === '-webkit-') {
+      return '::-webkit-file-upload-button'
+    }
+    return `::${prefix}file-selector-button`
+  }
+}
+
+FileSelectorButton.names = ['::file-selector-button']
+
+module.exports = FileSelectorButton