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/tailwindcss/lib/postcss-plugins/nesting/README.md

@@ -0,0 +1,42 @@
+# tailwindcss/nesting
+
+This is a PostCSS plugin that wraps [postcss-nested](https://github.com/postcss/postcss-nested) or [postcss-nesting](https://github.com/csstools/postcss-plugins/tree/main/plugins/postcss-nesting) and acts as a compatibility layer to make sure your nesting plugin of choice properly understands Tailwind's custom syntax like `@apply` and `@screen`.
+
+Add it to your PostCSS configuration, somewhere before Tailwind itself:
+
+```js
+// postcss.config.js
+module.exports = {
+  plugins: [
+    require('postcss-import'),
+    require('tailwindcss/nesting'),
+    require('tailwindcss'),
+    require('autoprefixer'),
+  ]
+}
+```
+
+By default, it uses the [postcss-nested](https://github.com/postcss/postcss-nested) plugin under the hood, which uses a Sass-like syntax and is the plugin that powers nesting support in the [Tailwind CSS plugin API](https://tailwindcss.com/docs/plugins#css-in-js-syntax).
+
+If you'd rather use [postcss-nesting](https://github.com/csstools/postcss-plugins/tree/main/plugins/postcss-nesting) (which is based on the work-in-progress [CSS Nesting](https://drafts.csswg.org/css-nesting-1/) specification), first install the plugin alongside:
+
+```shell
+npm install postcss-nesting
+```
+
+Then pass the plugin itself as an argument to `tailwindcss/nesting` in your PostCSS configuration:
+
+```js
+// postcss.config.js
+module.exports = {
+  plugins: [
+    require('postcss-import'),
+    require('tailwindcss/nesting')(require('postcss-nesting')),
+    require('tailwindcss'),
+    require('autoprefixer'),
+  ]
+}
+```
+
+This can also be helpful if for whatever reason you need to use a very specific version of `postcss-nested` and want to override the version we bundle with `tailwindcss/nesting` itself.
+