feat(plugins): implement Sprint 5 documentation and fixes (#266-#269)

Release v5.2.0

Documentation:
- Add git-flow branching strategy guide (docs/BRANCHING-STRATEGY.md)
- Add clarity-assist ND support documentation (docs/ND-SUPPORT.md)
- Update DEBUGGING-CHECKLIST.md with Gitea auto-close behavior and MCP restart notes
- Update plugin READMEs to reference new documentation

Bug Fix:
- Add milestone parameter to update_issue MCP tool (gitea_client.py, server.py, tools/issues.py)

Version Updates:
- Marketplace version: 5.1.0 → 5.2.0
- README title: v5.1.0 → v5.2.0
- CHANGELOG: [Unreleased] → [5.2.0] - 2026-01-28

Closes #266, Closes #267, Closes #268, Closes #269

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

mcp-servers/gitea/mcp_server/tools/issues.py

@@ -200,6 +200,7 @@ class IssueTools:
         body: Optional[str] = None,
         state: Optional[str] = None,
         labels: Optional[List[str]] = None,
+        milestone: Optional[int] = None,
         repo: Optional[str] = None
     ) -> Dict:
         """
@@ -211,6 +212,7 @@ class IssueTools:
             body: New body (optional)
             state: New state - 'open' or 'closed' (optional)
             labels: New labels (optional)
+            milestone: Milestone ID to assign (optional)
             repo: Override configured repo (for PMO multi-repo)
 
         Returns:
@@ -229,7 +231,7 @@ class IssueTools:
         loop = asyncio.get_event_loop()
         return await loop.run_in_executor(
             None,
-            lambda: self.gitea.update_issue(issue_number, title, body, state, labels, repo)
+            lambda: self.gitea.update_issue(issue_number, title, body, state, labels, milestone, repo)
         )
 
     async def add_comment(