chore: update .gitignore to exclude personal workspace and generated onboard content

- Restore cmd/sofia/internal/onboard/workspace/ and antigravity-kit/ to ignored (generated by go:generate)
- Add CLAUDE.md and .claude/ exclusions
- Add patterns to exclude session and AI-generated work docs

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: grasberg

.gitignore

@@ -1,8 +1,6 @@
 # Binaries / build artifacts
 bin/
 build/
-cmd/sofia/internal/onboard/workspace/
-cmd/sofia/internal/onboard/antigravity-kit/
 *.exe
 *.dll
 *.so
@@ -25,6 +23,10 @@ workspace/plans.json
 workspace/heartbeat.log
 workspace/.DS_Store
 
+# Onboard embedded workspace — generated by go:generate, not tracked
+cmd/sofia/internal/onboard/workspace/
+cmd/sofia/internal/onboard/antigravity-kit/
+
 # Secrets
 .env
 .env.local
@@ -53,3 +55,14 @@ ralph/
 .ralph/
 tasks/
 claude.md
+CLAUDE.md
+.claude/
+
+# Session / AI-generated work docs
+BUG_FIXES*.md
+WORKFLOW_*.md
+OLLAMA_*.md
+REFACTOR*.md
+REFACTORING*.md
+docs/OLLAMA_*/
+docs/REFACTOR*/