docs: update CLAUDE.md to require branch and PR workflow

Clarify that commits should never go directly to main. All work must go through
feature branches and pull requests for review and traceability.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

CLAUDE.md

@@ -115,6 +115,16 @@ The authenticated email comes from `securityIdentity.getPrincipal().getName()` a
 - Don't create files outside the conventional folders.
 - Vertical slices first; refactor when a pattern repeats. The backlog is in `backlog.md`.
 
+## Git Workflow
+
+**Never commit directly to `main`.** Always:
+1. Create a feature branch: `git checkout -b feature/short-description`
+2. Make commits to the branch
+3. Create a pull request (GitHub) for review
+4. Merge via PR after approval
+
+This ensures code review, clear history, and traceability.
+
 ## Skills
 
 Skills do projeto em `.claude/skills/`: