Move to dedicated Postgres and netbird-only SSH; DB password to .env

docker-compose.yml had drifted from the committed version during the move to
this host: a dedicated gitea-postgres service replaces the shared postgres-db
on the LAN box, and SSH is now published on the netbird interface only
(100.75.252.111:2222) instead of 0.0.0.0.

The database password is no longer inline — both POSTGRES_PASSWORD and
GITEA__database__PASSWD read ${POSTGRES_PASSWORD} from .env (gitignored,
mode 0600). .env.example documents the key, and *.bak-* is now ignored.

Note: run docker compose from this directory, otherwise .env is not picked up
and the variable resolves empty.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Kjn2zm5PJ5y9t4HjpGouWR

.env.example

@@ -0,0 +1,2 @@
+# Copy to .env and fill in. Used by docker-compose.yml.
+POSTGRES_PASSWORD=change-me

.gitignore

@@ -1,3 +1,4 @@
 *.zip
 *.log
 .env
+*.bak-*

docker-compose.yml

@@ -1,24 +1,37 @@
 services:
+  postgres:
+    image: postgres:16-alpine
+    container_name: gitea-postgres
+    restart: unless-stopped
+    environment:
+      - POSTGRES_USER=gitea
+      - POSTGRES_PASSWORD=${POSTGRES_PASSWORD}
+      - POSTGRES_DB=gitea
+    volumes:
+      - postgres_data:/var/lib/postgresql/data
+
   gitea:
     image: gitea/gitea:latest
     container_name: gitea
+    depends_on:
+      - postgres
     environment:
       - USER_UID=1000
       - USER_GID=1000
       - GITEA__database__DB_TYPE=postgres
-      - GITEA__database__HOST=192.168.50.42:5432
+      - GITEA__database__HOST=postgres:5432
       - GITEA__database__NAME=gitea
-      - GITEA__database__USER=postgres
-      - GITEA__database__PASSWD=ratata,123
+      - GITEA__database__USER=gitea
+      - GITEA__database__PASSWD=${POSTGRES_PASSWORD}
     restart: unless-stopped
     volumes:
       - gitea_data:/data
       - /etc/timezone:/etc/timezone:ro
       - /etc/localtime:/etc/localtime:ro
-      - /data/backup/gitea:/tmp/backup
+      - ./backup:/tmp/backup
     ports:
       - "3008:3000"
-      - "2222:22"
+      - "100.75.252.111:2222:22"
 
   gitea-backup:
     image: alpine:3.21
@@ -30,7 +43,7 @@ services:
       - BACKUP_RETAIN_DAYS=7
     volumes:
       - /var/run/docker.sock:/var/run/docker.sock
-      - /data/backup/gitea:/backup
+      - ./backup:/backup
       - ./backup.sh:/usr/local/bin/backup.sh:ro
       - /etc/timezone:/etc/timezone:ro
       - /etc/localtime:/etc/localtime:ro
@@ -45,3 +58,4 @@ services:
 
 volumes:
   gitea_data:
+  postgres_data: