refactor: rename Gitea environment variables to CI registry prefix

update SETUP.md and .env.example

.env.example

@@ -31,10 +31,12 @@ ADMIN_SESSION_TTL_HOURS=12
 # VITE_PUBLIC_HLS_URL=http://localhost/hls/playlist.m3u8
 
 # Gitea Container Registry (for self-hosted Docker images)
-GITEA_REGISTRY_URL=git.allucanget.biz
-GITEA_USERNAME=your-gitea-username
-GITEA_TOKEN=your-gitea-token
-GITEA_REGISTRY_NAMESPACE=zwitschi/linearvoid
+CI_REGISTRY_URL=git.allucanget.biz
+CI_REGISTRY_USER=your-gitea-username
+CI_REGISTRY_TOKEN=your-gitea-token
+CI_REGISTRY_NAMESPACE=zwitschi/linearvoid
+# Gitea API access (optional, for CI/release automation)
+CI_SERVER_URL=https://git.allucanget.biz
 
 # Chat / Application Database (compose-safe PostgreSQL by default, SQLite optional)
 DATABASE_URL=postgres://linearvoid:linearvoid@db:5432/linearvoid?sslmode=disable
@@ -61,9 +63,4 @@ GRAFANA_PORT=3001
 
 # Development flags
 NODE_ENV=development
-GO_ENV=development
-
-# Gitea Configuration
-GITEA_SERVER_URL=https://git.allucanget.biz
-GITEA_TOKEN=your-gitea-token
-GITEA_USERNAME=your-gitea-username
+GO_ENV=development