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-executor.test.ts

@@ -8,14 +8,14 @@ import {
 	type PythonKernelExecutor,
 	resetPreludeDocsCache,
 	warmPythonEnvironment,
-} from "../../src/core/python-executor";
+} from "$c/core/python-executor";
 import {
 	type KernelExecuteOptions,
 	type KernelExecuteResult,
 	type PreludeHelper,
 	PythonKernel,
-} from "../../src/core/python-kernel";
-import { DEFAULT_MAX_BYTES } from "../../src/core/tools/truncate";
+} from "$c/core/python-kernel";
+import { DEFAULT_MAX_BYTES } from "$c/core/tools/truncate";
 
 class FakeKernel implements PythonKernelExecutor {
 	private result: KernelExecuteResult;