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/argparse/lib/argument/error.js

@@ -0,0 +1,50 @@
+'use strict';
+
+
+var format  = require('util').format;
+
+
+var ERR_CODE = 'ARGError';
+
+/*:nodoc:*
+ * argumentError(argument, message) -> TypeError
+ * - argument (Object): action with broken argument
+ * - message (String): error message
+ *
+ * Error format helper. An error from creating or using an argument
+ * (optional or positional). The string value of this exception
+ * is the message, augmented with information
+ * about the argument that caused it.
+ *
+ * #####Example
+ *
+ *      var argumentErrorHelper = require('./argument/error');
+ *      if (conflictOptionals.length > 0) {
+ *        throw argumentErrorHelper(
+ *          action,
+ *          format('Conflicting option string(s): %s', conflictOptionals.join(', '))
+ *        );
+ *      }
+ *
+ **/
+module.exports = function (argument, message) {
+  var argumentName = null;
+  var errMessage;
+  var err;
+
+  if (argument.getName) {
+    argumentName = argument.getName();
+  } else {
+    argumentName = '' + argument;
+  }
+
+  if (!argumentName) {
+    errMessage = message;
+  } else {
+    errMessage = format('argument "%s": %s', argumentName, message);
+  }
+
+  err = new TypeError(errMessage);
+  err.code = ERR_CODE;
+  return err;
+};