feat: replace custom Gitea client with MCP servers

Replace the bespoke GiteaHand httpx client and tools_gitea.py wrappers
with official MCP tool servers (gitea-mcp + filesystem MCP), wired into
Agno via MCPTools. Switch all session functions to async (arun/acontinue_run)
so MCP tools auto-connect. Delete ~1070 lines of custom Gitea code.

- Create src/timmy/mcp_tools.py with MCP factories + standalone issue bridge
- Wire MCPTools into agent.py tool list (Gitea + filesystem)
- Switch session.py chat/chat_with_tools/continue_chat to async
- Update all callers (dashboard routes, Discord vendor, CLI, thinking engine)
- Add gitea_token fallback from ~/.config/gitea/token
- Add MCP session cleanup to app shutdown hook
- Update tool_safety.py for MCP tool names
- 11 new tests, all 1417 passing, coverage 74.2%

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

src/dashboard/routes/chat_api.py

@@ -88,7 +88,7 @@ async def api_chat(request: Request):
             f"{now.strftime('%A, %B %d, %Y at %I:%M %p')}]\n"
             f"[System: Mobile client]\n\n"
         )
-        response_text = agent_chat(
+        response_text = await agent_chat(
             context_prefix + last_user_msg,
             session_id="mobile",
         )