test: migrated test imports to package subpath exports

- Replaced relative `../src` imports with `@oh-my-pi/pi-ai` and `@oh-my-pi/pi-agent-core` subpaths.

packages/coding-agent/test/bash-failure-result.test.ts

@@ -1,6 +1,6 @@
 import { describe, expect, it } from "bun:test";
-import type { ToolSession } from "../src/tools";
-import { BashTool } from "../src/tools/bash";
+import type { ToolSession } from "@oh-my-pi/pi-coding-agent/tools";
+import { BashTool } from "@oh-my-pi/pi-coding-agent/tools/bash";
 
 function makeSession(): ToolSession {
 	return {