chore(frontend): exclude .worktrees from vitest discovery

vitest.config.ts

@@ -17,5 +17,13 @@ export default defineConfig({
     env: {
       VITE_API_BASE_URL: "http://test.local",
     },
+    // Skip sibling worktrees + their node_modules so each worktree only runs
+    // its own tests. Without this, vitest walks up the tree and re-runs the
+    // main checkout's tests from inside the worktree, inflating the count.
+    exclude: [
+      "**/node_modules/**",
+      "**/dist/**",
+      ".worktrees/**",
+    ],
   },
 });