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/docmost/.felhom.yml

@@ -29,6 +29,14 @@ deploy_fields:
     description: "A szerver domain neve"
     locked_after_deploy: true
 
+  - env_var: SUBDOMAIN
+    label: "Aldomain"
+    type: subdomain
+    default: "docs"
+    required: true
+    locked_after_deploy: true
+    description: "Az alkalmazás aldomainje"
+
   - env_var: APP_SECRET
     label: "Alkalmazás titkosítási kulcs"
     type: secret

templates/docmost/docker-compose.yml

@@ -1,5 +1,5 @@
 # Docmost - Modern Wiki / Documentation (Notion-like)
-# Domain: docs.${DOMAIN}
+# Domain: ${SUBDOMAIN}.${DOMAIN}
 # Database: PostgreSQL + Redis
 # RAM: ~200MB (mem_limit: 768M total — docmost 384M + postgres 256M + redis 128M) | Pi-compatible: No (heavy)
 #
@@ -25,7 +25,7 @@ services:
       - APP_SECRET=${APP_SECRET}
       - DATABASE_URL=postgresql://docmost:${DB_PASSWORD}@docmost-postgres:5432/docmost
       - REDIS_URL=redis://docmost-redis:6379
-      - APP_URL=https://docs.${DOMAIN}
+      - APP_URL=https://${SUBDOMAIN}.${DOMAIN}
       - STORAGE_DRIVER=local
       - FILE_UPLOAD_SIZE_LIMIT=50mb
       - TZ=Europe/Budapest
@@ -46,7 +46,7 @@ services:
       start_period: 30s
     labels:
       - "traefik.enable=true"
-      - "traefik.http.routers.docmost.rule=Host(`docs.${DOMAIN}`)"
+      - "traefik.http.routers.docmost.rule=Host(`${SUBDOMAIN}.${DOMAIN}`)"
       - "traefik.http.routers.docmost.entrypoints=websecure"
       - "traefik.http.routers.docmost.tls=true"
       - "traefik.http.routers.docmost.tls.certresolver=letsencrypt"