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-testing.md

@@ -1,31 +0,0 @@
----
-description: "Go testing: table-driven tests, race detection, coverage reporting"
-globs: ["**/*.go"]
-alwaysApply: false
----
-
-# Go Testing
-
-> This file extends [common/testing.md](../common/testing.md) with Go specific content.
-
-## Framework
-
-Use the standard `go test` with **table-driven tests**.
-
-## Race Detection
-
-Always run with the `-race` flag:
-
-```bash
-go test -race ./...
-```
-
-## Coverage
-
-```bash
-go test -cover ./...
-```
-
-## Reference
-
-See skill: `golang-testing` for detailed Go testing patterns and helpers.