refactor(build): migrated imports to path aliases with per-package tsconfig support

- converted relative imports to path aliases ($c/*, $ai/*, $tui/*, etc.) across all packages
- added per-package tsconfig.json with complete path mappings for runtime resolution
- set importModuleSpecifier to non-relative for IDE auto-import preferences
- updated dev script to run from monorepo root for consistent path resolution

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

@@ -2,7 +2,7 @@ import { afterEach, beforeEach, describe, expect, it } from "bun:test";
 import { rmSync } from "node:fs";
 import { createTempDirSync, type SyncTempDir } from "@oh-my-pi/pi-utils";
 import type { Subprocess } from "bun";
-import { PythonKernel } from "../../src/core/python-kernel";
+import { PythonKernel } from "$c/core/python-kernel";
 
 type SpawnOptions = Parameters<typeof Bun.spawn>[1];