feat(coding-agent/eval): added local python-runner subprocess execution

- Replaced Python execution with a local `python -u runner.py` subprocess and NDJSON stdin/stdout framing.
- Removed shared-gateway architecture, including coordinator lifecycle APIs, `useSharedGateway` wiring, and `jupyter` CLI/actions.
- Simplified setup checks to a plain Python 3 availability probe and removed automatic dependency-install fallbacks.
- Updated kernel cancellation and display processing to use status frames, SIGINT/SIGTERM escalation, and normalized output coercion.
- Added `python-runner` integration and display tests while deleting legacy websocket and kernel lifecycle test suites.

packages/coding-agent/src/commands/jupyter.ts

@@ -1,32 +0,0 @@
-/**
- * Manage the shared Jupyter gateway.
- */
-import { Args, Command } from "@oh-my-pi/pi-utils/cli";
-import { type JupyterAction, type JupyterCommandArgs, runJupyterCommand } from "../cli/jupyter-cli";
-import { initTheme } from "../modes/theme/theme";
-
-const ACTIONS: JupyterAction[] = ["kill", "status"];
-
-export default class Jupyter extends Command {
-	static description = "Manage the shared Jupyter gateway";
-
-	static args = {
-		action: Args.string({
-			description: "Jupyter action",
-			required: false,
-			options: ACTIONS,
-		}),
-	};
-
-	async run(): Promise<void> {
-		const { args } = await this.parse(Jupyter);
-		const action = (args.action ?? "status") as JupyterAction;
-
-		const cmd: JupyterCommandArgs = {
-			action,
-		};
-
-		await initTheme();
-		await runJupyterCommand(cmd);
-	}
-}