refactor(repo): replace legacy openflare-server with Wavelet rename

Delete the old monolithic openflare-server implementation and rename
Wavelet/ to openflare-server/ to complete the migration consolidation.
Update CI workflows, agent Dockerfiles, and deployment docs for the new
layout (frontend/, docker/Dockerfile).

openflare-server/frontend/.env.example

@@ -0,0 +1,11 @@
+# 前端 URL
+WAVELET_FRONTEND_URL=http://localhost:3000
+
+# 后端 URL
+WAVELET_BACKEND_URL=http://localhost:3000
+
+# Session Cookie
+WAVELET_SESSION_COOKIE_NAME=openflare_session_id
+
+# 环境
+NODE_ENV=production