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/d3-scale-chromatic/README.md

@@ -0,0 +1,12 @@
+# d3-scale-chromatic
+
+<a href="https://d3js.org"><img src="https://github.com/d3/d3/raw/main/docs/public/logo.svg" width="256" height="256"></a>
+
+This module provides sequential, diverging and categorical color schemes designed to work with [d3-scale](https://github.com/d3/d3-scale)’s scaleOrdinal and scaleSequential. Most of these schemes are derived from Cynthia A. Brewer’s [ColorBrewer](http://colorbrewer2.org). Since ColorBrewer publishes only discrete color schemes, the sequential and diverging scales are interpolated using [uniform B-splines](https://observablehq.com/@d3/colorbrewer-splines).
+
+## Resources
+
+- [Documentation](https://d3js.org/d3-scale-chromatic)
+- [Examples](https://observablehq.com/collection/@d3/d3-scale-chromatic)
+- [Releases](https://github.com/d3/d3-scale-chromatic/releases)
+- [Getting help](https://d3js.org/community)