feat: add more tested common patterns to reduce agent discovery time

- Add Git push conflict handling patterns (tested)
- Add PR number extraction patterns (tested)
- Document these patterns agents frequently need
- Keep branch protection as untested pattern

These patterns save time for agents that work with git and PRs.

.opencode/agents/COMMON_PATTERNS.md

@@ -129,12 +129,43 @@ The project uses the monolithic format:
 
 Note: The split format (`docs/specification/`) is not used in this project.
 
+### Git Push Conflict Handling
+
+**Status**: ✅ TESTED (used by multiple agents)
+
+When `git push` is rejected due to diverged branches:
+```bash
+git pull --rebase origin <branch> && git push
+```
+
+For force push (use sparingly and only on feature branches):
+```bash
+git push --force-with-lease  # Safer than --force
+```
+
 ### Branch Protection Settings
 
 **Status**: ⚠️ UNTESTED (assumed defaults)
 
 Default for master/main:
-- Require CI checks to pass
+- Require CI checks to pass  
 - Dismiss stale reviews
 - No force push allowed
-- No deletion allowed
+- No deletion allowed
+
+### PR Number Extraction Patterns
+
+**Status**: ✅ TESTED
+
+Extract PR number from various sources:
+```python
+# From PR title/branch name
+pr_pattern = r'PR[-#]?(\d+)'
+
+# From PR body closing keywords
+closes_pattern = r'(?:Closes|Fixes|Resolves)\s*#(\d+)'
+
+# From action run URLs
+run_pattern = r'/actions/runs/(\d+)'
+job_pattern = r'/actions/runs/\d+/jobs/(\d+)'
+```