chore(.gitignore): exclude .env + .env.* with .env.example carve-out

Secures the workspace against accidental commits of:
- .env (skill env overrides, may contain secrets)
- .env.* (any env variant)
- except .env.example (committable template, can be added later)

Includes Korean comment noting secrets policy.

.gitignore

@@ -13,6 +13,11 @@ test-sessions*.yaml.lock
 __pycache__/
 *.pyc
 
+# 로컬 환경변수 (secrets — 절대 커밋 금지)
+.env
+.env.*
+!.env.example
+
 # 빌드/배포 HTML 산출물
 skills/tmux-agent-orchestrate-delegate-job/USER_MANUAL.html
 skills/tmux-agent-orchestrate-delegate-job/mqtt-broker-setup.html