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/monitoring/prometheus/targets/extra.yml.example

@@ -0,0 +1,7 @@
+# Hernoem naar extra.yml of merge handmatig. Formaat: lijst van static config groepen.
+#
+# Proxmox VE exporter (github.com/prometheus-pve/prometheus-pve-exporter):
+- targets:
+    - "192.168.1.50:9221"
+  labels:
+    instance: proxmox