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/string-length/index.d.ts

@@ -0,0 +1,22 @@
+/**
+Get the real length of a string - by correctly counting astral symbols and ignoring [ansi escape codes](https://github.com/sindresorhus/strip-ansi).
+
+`String#length` erroneously counts [astral symbols](https://web.archive.org/web/20150721114550/http://www.tlg.uci.edu/~opoudjis/unicode/unicode_astral.html) as two characters.
+
+@example
+```
+import stringLength = require('string-length');
+
+'🐴'.length;
+//=> 2
+
+stringLength('🐴');
+//=> 1
+
+stringLength('\u001B[1municorn\u001B[22m');
+//=> 7
+```
+*/
+declare function stringLength(string: string): number;
+
+export = stringLength;