Add Claude agents and review-and-commit skill

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

.claude/agents/test-isolation.md

@@ -0,0 +1,14 @@
+---
+description: Tests must be self-contained; mock external service dependencies
+globs: "**/*_test.go"
+alwaysApply: false
+---
+
+# Test Isolation
+
+Tests must be self-contained. The only shared infrastructure allowed is the database.
+
+- **Database**: tests may depend on a real database connection — this is expected and acceptable.
+- **External services** (gRPC clients, HTTP APIs, third-party SDKs, etc.): must be mocked or stubbed. Tests must never make real calls to external services.
+- Use interfaces for service dependencies so they are straightforward to mock in tests.
+- Keep mocks minimal — only stub the methods the test actually exercises.