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/calcom/.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: "cal"
+    required: true
+    locked_after_deploy: true
+    description: "Az alkalmazás aldomainje"
+
   - env_var: NEXTAUTH_SECRET
     label: "NextAuth titkosítási kulcs"
     type: secret

templates/calcom/docker-compose.yml

@@ -1,5 +1,5 @@
 # Cal.com - Nyílt forráskódú időpontfoglaló (Calendly alternatíva)
-# Domain: cal.${DOMAIN}
+# Domain: ${SUBDOMAIN}.${DOMAIN}
 # Database: postgres
 # RAM: ~200M (mem_limit: 768M) | Pi-compatible: No
 #
@@ -21,8 +21,8 @@ services:
       - NEXTAUTH_SECRET=${NEXTAUTH_SECRET}
       - CALENDSO_ENCRYPTION_KEY=${CALENDSO_ENCRYPTION_KEY}
       - DATABASE_URL=postgresql://calcom:${DB_PASSWORD}@calcom-postgres:5432/calcom
-      - NEXT_PUBLIC_WEBAPP_URL=https://cal.${DOMAIN}
-      - NEXTAUTH_URL=https://cal.${DOMAIN}
+      - NEXT_PUBLIC_WEBAPP_URL=https://${SUBDOMAIN}.${DOMAIN}
+      - NEXTAUTH_URL=https://${SUBDOMAIN}.${DOMAIN}
     networks:
       - traefik-public
       - calcom-internal
@@ -38,7 +38,7 @@ services:
       start_period: 30s
     labels:
       - "traefik.enable=true"
-      - "traefik.http.routers.calcom.rule=Host(`cal.${DOMAIN}`)"
+      - "traefik.http.routers.calcom.rule=Host(`${SUBDOMAIN}.${DOMAIN}`)"
       - "traefik.http.routers.calcom.entrypoints=websecure"
       - "traefik.http.routers.calcom.tls=true"
       - "traefik.http.routers.calcom.tls.certresolver=letsencrypt"