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/proxmox/hosts/dell-proxmox/qemu-server/104.conf

@@ -0,0 +1,15 @@
+boot: order=scsi0;ide2;net0
+cores: 4
+cpu: host
+ide2: none,media=cdrom
+memory: 4096
+meta: creation-qemu=9.2.0,ctime=1776633877
+name: kassa-dev
+net0: virtio=BC:24:11:12:44:B7,bridge=vmbr0,firewall=1
+numa: 0
+ostype: l26
+scsi0: local-lvm:vm-104-disk-0,iothread=1,size=32G
+scsihw: virtio-scsi-single
+smbios1: uuid=15ecdbd4-d955-4546-a881-18f2f85acf52
+sockets: 1
+vmgenid: 42878df4-eecf-4e21-9364-dbb65a4faab1