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-patterns.md

@@ -1,36 +0,0 @@
----
-description: "Common design patterns: skeleton projects, repository pattern, API response format"
-alwaysApply: true
----
-
-# Common Patterns
-
-## Skeleton Projects
-
-When implementing new functionality:
-1. Search for battle-tested skeleton projects
-2. Use parallel agents to evaluate options:
-   - Security assessment
-   - Extensibility analysis
-   - Relevance scoring
-   - Implementation planning
-3. Clone best match as foundation
-4. Iterate within proven structure
-
-## Design Patterns
-
-### Repository Pattern
-
-Encapsulate data access behind a consistent interface:
-- Define standard operations: findAll, findById, create, update, delete
-- Concrete implementations handle storage details (database, API, file, etc.)
-- Business logic depends on the abstract interface, not the storage mechanism
-- Enables easy swapping of data sources and simplifies testing with mocks
-
-### API Response Format
-
-Use a consistent envelope for all API responses:
-- Include a success/status indicator
-- Include the data payload (nullable on error)
-- Include an error message field (nullable on success)
-- Include metadata for paginated responses (total, page, limit)