fix: address PR review findings

- Revert undici to v7.27.1 (v8 blocked by #5467 qBittorrent regression)
- Broaden cache invalidation to utils.integration.invalidate() (covers
  all integration queries, not just integration.all)
- Add invalidation to onboarding integration create path
- Harden renovate test to assert allowBuilds key exists
- Remove deprecated Vitest 4 poolOptions config
- Fix CSS typo in docs menu transition (0.s → 0.5s)
- Update renovate.json5 comment to reference allowBuilds

.github/renovate.json5

@@ -22,7 +22,7 @@
       automerge: true,
     },
     {
-      // disallow automerge for onlyBuiltDependencies
+      // disallow automerge for allowBuilds dependencies (native builds need manual verification)
       matchPackageNames: [
         "@tree-sitter-grammars/tree-sitter-yaml",
         "bcrypt",