Reorganize repo: one folder per application under apps/.

Move docker/ and configs/ into apps/<name>/ with config/ subfolders.
Proxmox split into hosts/pve and hosts/dell-proxmox. Nginx under
infrastructure/. Update sync script, RESTORE.md, and per-app READMEs.

Co-authored-by: Cursor <cursoragent@cursor.com>

apps/postgres/docker-compose.yml

@@ -0,0 +1,17 @@
+# PostgreSQL — centrale homelab-database (poort 5433 op host).
+# NAS-pad: /volume1/docker/postgres/
+# Start:   cp .env.example .env && docker compose up -d
+
+services:
+  postgres-homelab:
+    image: postgres:16-alpine
+    container_name: postgres-homelab
+    restart: unless-stopped
+    ports:
+      - "${PG_HOST_PORT:-5433}:5432"
+    environment:
+      POSTGRES_USER: ${POSTGRES_USER:-mo}
+      POSTGRES_PASSWORD: ${POSTGRES_PASSWORD:-WaQTUw2t}
+      POSTGRES_DB: ${POSTGRES_DB:-homelab}
+    volumes:
+      - ${PG_DATA_DIR:-/volume1/docker/postgres/data}:/var/lib/postgresql/data