fix(homeassistant): its MCP tools register, stating read_only as the server requires (#6355)

Without it the plugin's hook raised at boot and left it with no tools. The
test's stand-in for register gave read_only a default, so now both arguments
are required there too.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

plugins/homeassistant/mcp_tools.py

@@ -108,4 +108,4 @@ async def mcp_overview(db) -> list[dict]:
 
 def register_tools(register) -> None:
     register(get_home_assistant, role=UserRole.viewer, read_only=True)
-    register(update_home_assistant, role=UserRole.admin)
+    register(update_home_assistant, role=UserRole.admin, read_only=False)