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/excalidraw/docker-compose.yml

@@ -0,0 +1,13 @@
+version: "3.9"
+services:
+  excalidraw:
+    container_name: Excalidraw
+    healthcheck:
+     test: curl -f http://localhost:80/ || exit 1
+    image: excalidraw/excalidraw:latest
+    ports:
+      - 3765:80
+    restart: on-failure:5
+    stdin_open: true
+    environment:
+      - NODE_ENV=production