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/src/cli/setup-cli.ts

@@ -6,8 +6,8 @@
 
 import { $ } from "bun";
 import chalk from "chalk";
-import { APP_NAME } from "../config";
-import { theme } from "../modes/interactive/theme/theme";
+import { APP_NAME } from "$c/config";
+import { theme } from "$c/modes/interactive/theme/theme";
 
 export type SetupComponent = "python";