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/server.py

@@ -168,6 +168,10 @@ class GiteaMCPServer:
                                 "items": {"type": "string"},
                                 "description": "New labels"
                             },
+                            "milestone": {
+                                "type": "integer",
+                                "description": "Milestone ID to assign"
+                            },
                             "repo": {
                                 "type": "string",
                                 "description": "Repository name (for PMO mode)"