chore: drop vestigial $lib alias

$lib pointed at src/lib/, which does not exist, and nothing imported it.
Removed the dead alias from all five declaration sites (tsconfig plus the
vite and three vitest configs). A stray $lib import now fails fast as an
unknown alias instead of resolving to a missing path.

vitest.config.browser.ts

@@ -23,7 +23,6 @@ export default defineConfig({
 
     resolve: {
         alias: {
-            $lib: path.resolve(__dirname, './src/lib'),
             $app: path.resolve(__dirname, './src/app'),
             $shared: path.resolve(__dirname, './src/shared'),
             $entities: path.resolve(__dirname, './src/entities'),