feat: add hooks and rules

.claude/rules/testing.md

@@ -0,0 +1,19 @@
+---
+paths:
+  - "**/*.test.*"
+  - "**/*.spec.*"
+  - "**/tests/**"
+  - "**/test_*"
+  - "**/__tests__/**"
+---
+
+# Test Writing Rules
+
+- Python test naming: `test_[function]_[scenario]_[expected]`
+- TypeScript test naming: `describe('[Component]', () => { it('should [behavior]') })`
+- Each test file must have at least one happy path and one error case
+- Mock external dependencies, not internal modules
+- Use factories/fixtures over inline test data
+- Never commit `.skip()` or `.only()` — remove before pushing
+- Minimum coverage: 80% overall, 95% for critical paths
+- Prefer pytest for Python, vitest for TypeScript