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/next/dist/pages/_error.d.ts

@@ -0,0 +1,18 @@
+import React from 'react';
+import type { NextPageContext } from '../shared/lib/utils';
+export type ErrorProps = {
+    statusCode: number;
+    title?: string;
+    withDarkMode?: boolean;
+};
+declare function _getInitialProps({ res, err, }: NextPageContext): Promise<ErrorProps> | ErrorProps;
+/**
+ * `Error` component used for handling errors.
+ */
+export default class Error<P = {}> extends React.Component<P & ErrorProps> {
+    static displayName: string;
+    static getInitialProps: typeof _getInitialProps;
+    static origGetInitialProps: typeof _getInitialProps;
+    render(): import("react/jsx-runtime").JSX.Element;
+}
+export {};