chore(llms-txt): add ISR cache rules and vitest server alias

Add ISR rules for llms_full.txt and root /llms.txt routes in
nuxt.config.ts. Add #server alias to vitest config for resolving
server utility imports in unit tests.

Author: lukeocodes

nuxt.config.ts

@@ -126,6 +126,8 @@ export default defineNuxtConfig({
     '/api/registry/provenance/**': { isr: true, cache: { maxAge: 365 * 24 * 60 * 60 } },
     '/api/registry/files/**': { isr: true, cache: { maxAge: 365 * 24 * 60 * 60 } },
     '/package/**/llms.txt': { isr: 3600 },
+    '/package/**/llms_full.txt': { isr: 3600 },
+    '/llms.txt': { isr: 3600 },
     '/api/registry/package-meta/**': { isr: 300 },
     '/:pkg/.well-known/skills/**': { isr: 3600 },
     '/:scope/:pkg/.well-known/skills/**': { isr: 3600 },