feat: use ${SUBDOMAIN} variable in all templates

All 51 docker-compose.yml: replaced hardcoded subdomain.${DOMAIN}
with ${SUBDOMAIN}.${DOMAIN} in Traefik labels, app env vars, and
comments.

All 51 .felhom.yml: added SUBDOMAIN deploy field (type: subdomain)
with default matching existing subdomain metadata value.

Works with felhom-controller v0.27.0 which validates and stores the
user-chosen subdomain in app.yaml. Existing deployed apps get
SUBDOMAIN auto-injected via InjectMissingFields() on next sync.

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

templates/claper/.felhom.yml

@@ -24,6 +24,14 @@ deploy_fields:
     description: "A szerver domain neve"
     locked_after_deploy: true
 
+  - env_var: SUBDOMAIN
+    label: "Aldomain"
+    type: subdomain
+    default: "present"
+    required: true
+    locked_after_deploy: true
+    description: "Az alkalmazás aldomainje"
+
   - env_var: SECRET_KEY_BASE
     label: "Titkosítási kulcs"
     type: secret

templates/claper/docker-compose.yml

@@ -1,5 +1,5 @@
 # Claper - Interaktív prezentáció és közönség bevonás
-# Domain: present.${DOMAIN}
+# Domain: ${SUBDOMAIN}.${DOMAIN}
 # Database: postgres
 # RAM: ~100M (mem_limit: 384M) | Pi-compatible: Yes
 #
@@ -19,7 +19,7 @@ services:
     environment:
       - DATABASE_URL=postgresql://claper:${DB_PASSWORD}@claper-postgres:5432/claper
       - SECRET_KEY_BASE=${SECRET_KEY_BASE}
-      - BASE_URL=https://present.${DOMAIN}
+      - BASE_URL=https://${SUBDOMAIN}.${DOMAIN}
     volumes:
       - claper_uploads:/app/priv/static/uploads
     networks:
@@ -37,7 +37,7 @@ services:
       start_period: 30s
     labels:
       - "traefik.enable=true"
-      - "traefik.http.routers.claper.rule=Host(`present.${DOMAIN}`)"
+      - "traefik.http.routers.claper.rule=Host(`${SUBDOMAIN}.${DOMAIN}`)"
       - "traefik.http.routers.claper.entrypoints=websecure"
       - "traefik.http.routers.claper.tls=true"
       - "traefik.http.routers.claper.tls.certresolver=letsencrypt"