Add admin-core frontend (Port 3008)

Next.js admin frontend for Core with 3 categories
(Communication, Infrastructure, Development), 13 modules,
2 roles (developer, ops), and 11 API proxy routes.
Includes docker-compose service and nginx SSL config.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

admin-core/.dockerignore

@@ -0,0 +1,8 @@
+node_modules
+.next
+.git
+.gitignore
+README.md
+*.log
+.env.local
+.env.*.local