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/cli.ts

@@ -55,7 +55,6 @@ const commands: CommandEntry[] = [
 	{ name: "config", load: () => import("./commands/config").then(m => m.default) },
 	{ name: "grep", load: () => import("./commands/grep").then(m => m.default) },
 	{ name: "grievances", load: () => import("./commands/grievances").then(m => m.default) },
-	{ name: "jupyter", load: () => import("./commands/jupyter").then(m => m.default) },
 	{ name: "plugin", load: () => import("./commands/plugin").then(m => m.default) },
 	{ name: "setup", load: () => import("./commands/setup").then(m => m.default) },
 	{ name: "shell", load: () => import("./commands/shell").then(m => m.default) },