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>

backend/target/debug/build/thiserror-b2739e9196d76776/invoked.timestamp

@@ -0,0 +1 @@
+This file has an mtime of when this was started.

backend/target/debug/build/thiserror-b2739e9196d76776/out/private.rs

@@ -0,0 +1,5 @@
+#[doc(hidden)]
+pub mod __private18 {
+    #[doc(hidden)]
+    pub use crate::private::*;
+}

backend/target/debug/build/thiserror-b2739e9196d76776/output

@@ -0,0 +1,5 @@
+cargo:rerun-if-changed=build/probe.rs
+cargo:rustc-check-cfg=cfg(error_generic_member_access)
+cargo:rustc-check-cfg=cfg(thiserror_nightly_testing)
+cargo:rustc-check-cfg=cfg(thiserror_no_backtrace_type)
+cargo:rerun-if-env-changed=RUSTC_BOOTSTRAP

backend/target/debug/build/thiserror-b2739e9196d76776/root-output

@@ -0,0 +1 @@
+/home/alvis/taskpile/backend/target/debug/build/thiserror-b2739e9196d76776/out