fix(mypy): add fast and full mypy modes (#3975)

`mypy` became very slow for the common path. This can make local
pre-commit runs very slow. Let's restore that.

- restore fast mirrors-mypy hook for local runs
- add optional mypy-full hook and docs so devs can match CI
- run full mypy in CI with a hint when failures occur

### Test Plan
- uv run pre-commit run mypy --all-files
- uv run pre-commit run mypy-full --hook-stage manual --all-files
- uv run --group dev --group type_checking mypy

src/llama_stack/providers/inline/agents/meta_reference/agent_instance.py

@@ -995,14 +995,17 @@ class ChatAgent(ShieldRunnerMixin):
         except json.JSONDecodeError as e:
             raise ValueError(f"Failed to parse arguments for tool call: {tool_call.arguments}") from e
 
-        result = await self.tool_runtime_api.invoke_tool(
-            tool_name=tool_name_str,
-            kwargs={
-                "session_id": session_id,
-                # get the arguments generated by the model and augment with toolgroup arg overrides for the agent
-                **args,
-                **self.tool_name_to_args.get(tool_name_str, {}),
-            },
+        result = cast(
+            ToolInvocationResult,
+            await self.tool_runtime_api.invoke_tool(
+                tool_name=tool_name_str,
+                kwargs={
+                    "session_id": session_id,
+                    # get the arguments generated by the model and augment with toolgroup arg overrides for the agent
+                    **args,
+                    **self.tool_name_to_args.get(tool_name_str, {}),
+                },
+            ),
         )
         logger.debug(f"tool call {tool_name_str} completed with result: {result}")
         return result