address review: remove .cursor/ duplicate, use is not None checks

Changes based on CodeRabbit review feedback:

1. Remove entire .cursor/ directory — it was an identical copy of the
   main skills/commands/agents/rules, causing maintenance drift.
   Users of Cursor can reference the canonical files directly.

2. Use explicit `is not None` checks instead of truthiness for
   parsed['input'] and parsed['output']. Empty strings or empty
   dicts are valid values that should be preserved.

.cursor/rules/common-testing.md

@@ -1,34 +0,0 @@
----
-description: "Testing requirements: 80% minimum coverage, TDD workflow, test types"
-alwaysApply: true
----
-
-# Testing Requirements
-
-## Minimum Test Coverage: 80%
-
-Test Types (ALL required):
-1. **Unit Tests** - Individual functions, utilities, components
-2. **Integration Tests** - API endpoints, database operations
-3. **E2E Tests** - Critical user flows (framework chosen per language)
-
-## Test-Driven Development
-
-MANDATORY workflow:
-1. Write test first (RED)
-2. Run test - it should FAIL
-3. Write minimal implementation (GREEN)
-4. Run test - it should PASS
-5. Refactor (IMPROVE)
-6. Verify coverage (80%+)
-
-## Troubleshooting Test Failures
-
-1. Use **tdd-guide** agent
-2. Check test isolation
-3. Verify mocks are correct
-4. Fix implementation, not tests (unless tests are wrong)
-
-## Agent Support
-
-- **tdd-guide** - Use PROACTIVELY for new features, enforces write-tests-first