security: remove hardcoded API key, require OPENAI_API_KEY env var

- Remove hardcoded key from 05-code-review-swarm.ts
- Remove 05-code-review-swarm.ts from .gitignore (key is gone, safe to publish)
- Add .env.example template
- 04-live-swarm.ts remains ignored (runtime key required)

Author: jovanSAPFIONEER

.env.example

@@ -0,0 +1,5 @@
+# Copy this file to .env and fill in your key.
+# .env is gitignored — never commit your real key.
+
+# OpenAI API key (required for examples/05-code-review-swarm.ts and examples/04-live-swarm.ts)
+OPENAI_API_KEY=sk-...

.gitignore

@@ -21,7 +21,6 @@ __pycache__/
 
 # Live demos (use real API keys - never commit)
 examples/04-live-swarm.ts
-examples/05-code-review-swarm.ts
 *.pyo
 .env
 .venv/