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/golang-security.md

@@ -1,34 +0,0 @@
----
-description: "Go security: environment variable secrets, gosec static analysis, context timeouts"
-globs: ["**/*.go"]
-alwaysApply: false
----
-
-# Go Security
-
-> This file extends [common/security.md](../common/security.md) with Go specific content.
-
-## Secret Management
-
-```go
-apiKey := os.Getenv("OPENAI_API_KEY")
-if apiKey == "" {
-    log.Fatal("OPENAI_API_KEY not configured")
-}
-```
-
-## Security Scanning
-
-- Use **gosec** for static security analysis:
-  ```bash
-  gosec ./...
-  ```
-
-## Context & Timeouts
-
-Always use `context.Context` for timeout control:
-
-```go
-ctx, cancel := context.WithTimeout(ctx, 5*time.Second)
-defer cancel()
-```