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/interfaces

@@ -0,0 +1,35 @@
+# network interface settings; autogenerated
+# Please do NOT modify this file directly, unless you know what
+# you're doing.
+#
+# If you want to manage parts of the network configuration manually,
+# please utilize the 'source' or 'source-directory' directives to do
+# so.
+# PVE will preserve these directives, but will NOT read its network
+# configuration from sourced files, so do not attempt to move any of
+# the PVE managed interfaces into external files!
+
+auto lo
+iface lo inet loopback
+
+iface enp1s0 inet manual
+
+iface eno1 inet manual
+
+iface enxc84bd6d674e6 inet manual
+
+auto vmbr0
+iface vmbr0 inet static
+	address 192.168.1.56/24
+	gateway 192.168.1.1
+	bridge-ports enp1s0
+	bridge-stp off
+	bridge-fd 0
+
+auto vmbr1
+iface vmbr1 inet dhcp
+	bridge-ports eno1
+	bridge-stp off
+	bridge-fd 0
+
+source /etc/network/interfaces.d/*