fix(coding-agent): addressed python cleanup review findings

fixed retained-kernel restart and owner cleanup edge cases during recovery and disposal

tracked async user_python hooks during disposal-sensitive execution paths and hardened startup warmup tracking

strengthened cleanup and kernel lifecycle regressions to remove deadlocks, false positives, and timing flakes

packages/coding-agent/test/core/python-executor.lifecycle.test.ts

@@ -3,6 +3,7 @@ import { disposeAllKernelSessions, executePython } from "@oh-my-pi/pi-coding-age
 import {
 	type KernelExecuteOptions,
 	type KernelExecuteResult,
+	type KernelShutdownResult,
 	PythonKernel,
 } from "@oh-my-pi/pi-coding-agent/ipy/kernel";
 
@@ -34,7 +35,7 @@ class FakeKernel {
 		return this.#result;
 	}
 
-	async shutdown(): Promise<{ confirmed: boolean }> {
+	async shutdown(): Promise<KernelShutdownResult> {
 		this.shutdownCalls += 1;
 		this.#alive = false;
 		return { confirmed: true };
@@ -173,11 +174,11 @@ describe("executePython session lifecycle", () => {
 			return kernels.shift() as unknown as PythonKernel;
 		};
 
-		kernelA.shutdown = async () => {
+		kernelA.shutdown = async (): Promise<KernelShutdownResult> => {
 			shutdownCount += 1;
 			return { confirmed: true };
 		};
-		kernelB.shutdown = async () => {
+		kernelB.shutdown = async (): Promise<KernelShutdownResult> => {
 			shutdownCount += 1;
 			return { confirmed: true };
 		};