feat: switch docker-compose template from port mapping to macvlan

Remove ports: section (no more host port mapping). Add networks:
with static ipv4_address for gitea and db containers. Reference
external gitea_net network (macvlan created by phase scripts).
Add DB_CONTAINER_IP for database service networking.

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

templates/docker-compose-gitea.yml.tpl

@@ -1,5 +1,5 @@
 # Gitea Docker Compose — rendered by phase1_gitea_unraid.sh and phase2_gitea_fedora.sh
-# Variables: GITEA_VERSION, DATA_PATH, GITEA_PORT, GITEA_SSH_PORT
+# Variables: GITEA_VERSION, DATA_PATH, GITEA_CONTAINER_IP
 # DATA_PATH is host-specific (UNRAID_GITEA_DATA_PATH or FEDORA_GITEA_DATA_PATH)
 # DB_SERVICE block is stripped for sqlite3, kept for mysql/postgres/mssql.
 
@@ -20,6 +20,9 @@ ${DB_ENV_VARS}
       interval: 10s
       timeout: 5s
       retries: 5
+    networks:
+      gitea_net:
+        ipv4_address: ${DB_CONTAINER_IP}
 # DB_SERVICE_END
 
   gitea:
@@ -39,12 +42,16 @@ ${DB_ENV_VARS}
       - ${DATA_PATH}/config:/data/gitea/conf       # app.ini lives here
       - /etc/timezone:/etc/timezone:ro
       - /etc/localtime:/etc/localtime:ro
-    ports:
+    networks:
-      - "${GITEA_PORT}:3000"        # Web UI + API
+      gitea_net:
-      - "${GITEA_SSH_PORT}:22"      # Git over SSH (host port 22 is taken by SSH server)
+        ipv4_address: ${GITEA_CONTAINER_IP}
     healthcheck:
       test: ["CMD", "curl", "-sf", "http://localhost:3000/api/v1/version"]
       interval: 30s
       timeout: 5s
       retries: 3
       start_period: 30s
+
+networks:
+  gitea_net:
+    external: true