infra: clean up Keycloak configuration, enforce consistency in .env, and improve health checks

Streamlined Keycloak configurations with defaults for development and production in `.env`. Added health checks and improved environment variable documentation with comments to differentiate local and server deployments. Ensured compatibility with pre-built registry images.

config/scripts/backup.sh

@@ -4,15 +4,25 @@
 #  Sichert Datenbanken und Konfigurationen
 # ==========================================
 
-# Konfiguration
-BACKUP_DIR="/home/grandmo/backups/meldestelle"
+# .env laden (SSoT für alle Variablen)
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+PROJECT_ROOT="$(cd "$SCRIPT_DIR/../.." && pwd)"
+if [ -f "$PROJECT_ROOT/.env" ]; then
+    set -a
+    # shellcheck disable=SC1091
+    source "$PROJECT_ROOT/.env"
+    set +a
+fi
+
+# Konfiguration (Defaults falls .env nicht vorhanden)
+BACKUP_DIR="${BACKUP_DIR:-$HOME/backups/meldestelle}"
 DATE=$(date +%Y-%m-%d_%H-%M-%S)
-RETENTION_DAYS=7
-PROJECT_NAME="meldestelle"
+RETENTION_DAYS="${BACKUP_RETENTION_DAYS:-7}"
+PROJECT_NAME="${PROJECT_NAME:-meldestelle}"
 
 # Container Namen (müssen mit docker-compose übereinstimmen)
 DB_CONTAINER="${PROJECT_NAME}-postgres"
-DB_USER="meldestelle" # Oder aus .env lesen
+DB_USER="${POSTGRES_USER:-pg-user}"
 
 # Verzeichnisse erstellen
 mkdir -p "$BACKUP_DIR"