refactor: resolve() internal links instead of plain hrefs

Type-checks every link against the real route tree. Caught a dead one: the
book page linked tags to /tag/{id}, a route that has never existed.

frontend/eslint.config.js

@@ -29,6 +29,12 @@ export default defineConfig(
 			'no-undef': 'off'
 		}
 	},
+	{
+		// Generated shadcn components take href as a prop and cannot resolve it —
+		// that is the caller's job. Editing them here would be lost on regeneration.
+		files: ['src/lib/components/ui/**'],
+		rules: { 'svelte/no-navigation-without-resolve': 'off' }
+	},
 	{
 		files: ['**/*.svelte', '**/*.svelte.ts', '**/*.svelte.js'],
 		languageOptions: {