refactor(deps): restructured codebase to use centralized pi-utils package

- Created new @oh-my-pi/pi-utils workspace package with shared utilities for logging, process management, stream handling, and temporary directory management.
- Migrated all packages to use centralized logger from @oh-my-pi/pi-utils instead of local winston implementations.
- Replaced custom process spawning and stream reading implementations with standardized cspawn and readLines utilities across all modules.
- Converted synchronous file operations and process spawning to async patterns using Bun shell syntax and fs/promises.
- Added streaming edit abort functionality with configurable setting to abort on patch preview failures.
- Updated test framework from vitest to bun:test across all test suites.

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

@@ -1,5 +1,6 @@
 import { afterEach, describe, expect, it, vi } from "bun:test";
 import { rmSync } from "node:fs";
+import { createTempDirSync } from "@oh-my-pi/pi-utils";
 import {
 	disposeAllKernelSessions,
 	executePythonWithKernel,
@@ -152,6 +153,7 @@ describe("warmPythonEnvironment", () => {
 	it("caches prelude docs on warmup", async () => {
 		const previousSkip = process.env.OMP_PYTHON_SKIP_CHECK;
 		process.env.OMP_PYTHON_SKIP_CHECK = "1";
+		using tempDir = createTempDirSync("@python-executor-");
 		const docs: PreludeHelper[] = [
 			{
 				name: "read",
@@ -168,7 +170,7 @@ describe("warmPythonEnvironment", () => {
 		};
 		const startSpy = vi.spyOn(PythonKernel, "start").mockResolvedValue(kernel as unknown as PythonKernel);
 
-		const result = await warmPythonEnvironment("/tmp/test", "session-1");
+		const result = await warmPythonEnvironment(tempDir.path, "session-1");
 
 		expect(result.ok).toBe(true);
 		expect(result.docs).toEqual(docs);