refactor(agents): group MCP tools into shared/tools/mcp/ subpackage

The three MCP siblings (mcp_client/mcp_tool/mcp_tools_cache) served one
objective but sat loose at the top of shared/tools. Grouped them into an
mcp/ package and dropped the redundant prefix: client.py, tool.py, cache.py.
Updated all importers (routes, mcp_tools subagent, e2e fake patch targets,
unit test) to the new paths.

surfsense_backend/app/agents/shared/tools/mcp/__init__.py

@@ -0,0 +1,7 @@
+"""MCP (Model Context Protocol) integration: client, tool loading, and cache.
+
+Split by responsibility:
+- ``client``: the low-level :class:`MCPClient` connection wrapper.
+- ``tool``: discovery + LangChain tool construction and cache invalidation.
+- ``cache``: the connector tool-cache refresh helpers.
+"""

surfsense_backend/app/agents/shared/tools/mcp/cache.py

@@ -112,7 +112,7 @@ def refresh_mcp_tools_cache_for_connector(
     when an event loop is available. Neither path raises.
     """
     try:
-        from app.agents.shared.tools.mcp_tool import invalidate_mcp_tools_cache
+        from app.agents.shared.tools.mcp.tool import invalidate_mcp_tools_cache
 
         invalidate_mcp_tools_cache(search_space_id)
     except Exception:
@@ -133,7 +133,7 @@ def refresh_mcp_tools_cache_for_connector(
 
 
 async def _run_connector_prefetch(connector_id: int) -> None:
-    from app.agents.shared.tools.mcp_tool import discover_single_mcp_connector
+    from app.agents.shared.tools.mcp.tool import discover_single_mcp_connector
 
     try:
         await discover_single_mcp_connector(connector_id)

surfsense_backend/app/agents/shared/tools/mcp/tool.py

@@ -35,8 +35,8 @@ from sqlalchemy.ext.asyncio import AsyncSession
 
 from app.agents.shared.middleware.dedup_tool_calls import dedup_key_full_args
 from app.agents.shared.tools.hitl import request_approval
-from app.agents.shared.tools.mcp_client import MCPClient
-from app.agents.shared.tools.mcp_tools_cache import (
+from app.agents.shared.tools.mcp.client import MCPClient
+from app.agents.shared.tools.mcp.cache import (
     CachedMCPTools,
     read_cached_tools,
     write_cached_tools,