chore(F.15): FastMCP 3.x upgrade + legacy cleanup — v3.5.0

- Upgrade fastmcp from >=2.14.0,<3.0.0 to >=3.0.0,<4.0.0
- Remove server_multi.py (legacy multi-endpoint server)
- Remove core/project_manager.py (legacy project manager)
- Refactor HealthMonitor to use SiteManager exclusively
- Replace _tool_manager._tools with tracked _tool_counts dict
- Clean core/__init__.py exports
- Update CHANGELOG, CLAUDE.md, tests
- Auto-format fixes (black + ruff)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

core/dashboard/routes.py

@@ -850,9 +850,7 @@ async def get_all_projects(
         is_admin = False
         current_user_id = None
         if user_session:
-            if hasattr(user_session, "user_type") and user_session.user_type == "master":
-                is_admin = True
-            elif isinstance(user_session, dict) and user_session.get("role") == "admin":
+            if hasattr(user_session, "user_type") and user_session.user_type == "master" or isinstance(user_session, dict) and user_session.get("role") == "admin":
                 is_admin = True
             elif isinstance(user_session, dict) and "user_id" in user_session:
                 current_user_id = user_session["user_id"]