Add ability to end a run as victory or defeat

Add End Run button to run dashboard with a confirmation modal offering
Victory/Defeat choice. Backend auto-sets completedAt timestamp and
validates only active runs can be ended. Ended runs show a completion
banner with date and duration, rename team to "Final Team", and hide
encounter logging and status change interactions.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/components/EndRunModal.tsx

@@ -0,0 +1,52 @@
+import type { RunStatus } from '../types'
+
+interface EndRunModalProps {
+  onConfirm: (status: RunStatus) => void
+  onClose: () => void
+  isPending?: boolean
+}
+
+export function EndRunModal({ onConfirm, onClose, isPending }: EndRunModalProps) {
+  return (
+    <div className="fixed inset-0 z-50 flex items-center justify-center">
+      <div className="fixed inset-0 bg-black/50" onClick={onClose} />
+      <div className="relative bg-white dark:bg-gray-800 rounded-lg shadow-xl max-w-md w-full mx-4">
+        <div className="px-6 py-4 border-b border-gray-200 dark:border-gray-700">
+          <h2 className="text-lg font-semibold">End Run</h2>
+        </div>
+        <div className="px-6 py-6">
+          <p className="text-gray-600 dark:text-gray-400 mb-6">
+            How did your run end?
+          </p>
+          <div className="flex flex-col gap-3">
+            <button
+              onClick={() => onConfirm('completed')}
+              disabled={isPending}
+              className="w-full px-4 py-3 rounded-lg font-medium text-left border-2 border-blue-200 dark:border-blue-800 bg-blue-50 dark:bg-blue-900/20 text-blue-700 dark:text-blue-300 hover:border-blue-400 dark:hover:border-blue-600 disabled:opacity-50 transition-colors"
+            >
+              <div className="font-semibold">Victory</div>
+              <div className="text-sm opacity-80">Beat the game successfully</div>
+            </button>
+            <button
+              onClick={() => onConfirm('failed')}
+              disabled={isPending}
+              className="w-full px-4 py-3 rounded-lg font-medium text-left border-2 border-red-200 dark:border-red-800 bg-red-50 dark:bg-red-900/20 text-red-700 dark:text-red-300 hover:border-red-400 dark:hover:border-red-600 disabled:opacity-50 transition-colors"
+            >
+              <div className="font-semibold">Defeat</div>
+              <div className="text-sm opacity-80">All Pokemon fainted or gave up</div>
+            </button>
+          </div>
+        </div>
+        <div className="px-6 py-4 border-t border-gray-200 dark:border-gray-700 flex justify-end">
+          <button
+            onClick={onClose}
+            disabled={isPending}
+            className="px-4 py-2 text-sm font-medium rounded-md border border-gray-300 dark:border-gray-600 hover:bg-gray-50 dark:hover:bg-gray-700"
+          >
+            Cancel
+          </button>
+        </div>
+      </div>
+    </div>
+  )
+}