feat: add Git operations tool for structured repository management

Implements #214 - Add git_operations tool that provides safe, parsed
git operations with JSON output and security policy integration.

Features:
- Operations: status, diff, log, branch, commit, add, checkout, stash
- Structured JSON output (parsed status, diff hunks, commit history)
- SecurityPolicy integration with autonomy-aware controls
- Command injection protection

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

src/agent/loop_.rs

@@ -477,6 +477,7 @@ pub async fn run(
         composio_key,
         &config.browser,
         &config.http_request,
+        &config.workspace_dir,
         &config.agents,
         config.api_key.as_deref(),
     );