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/commit-model-selection-role-thinking.test.ts

@@ -1,6 +1,6 @@
 import { describe, expect, it } from "bun:test";
 import { Effort, getBundledModel } from "@oh-my-pi/pi-ai";
-import { resolvePrimaryModel, resolveSmolModel } from "../src/commit/model-selection";
+import { resolvePrimaryModel, resolveSmolModel } from "@oh-my-pi/pi-coding-agent/commit/model-selection";
 
 function getModelOrThrow(id: string) {
 	const model = getBundledModel("anthropic", id);