feat(coding-agent): introduced stripInternalArgs utility to filter harness-internal keys

- Added stripInternalArgs() utility function to filter harness-internal keys from tool arguments.
- Hidden agent__intent parameter from UI and log displays across agent, session, MCP, and tool-execution components.
- Implemented HIDDEN_ARG_KEYS constant to centrally manage internal argument filtering.
- Updated formatArgsInline() to exclude internal keys when rendering tool arguments.

packages/coding-agent/src/commit/agentic/agent.ts

@@ -245,6 +245,7 @@ function formatToolArgs(args?: Record<string, unknown>): string[] {
 		}
 	};
 	for (const [key, value] of Object.entries(args)) {
+		if (key === "agent__intent") continue;
 		visit(value, key);
 	}
 	return lines;