nfs-mirror: append transferred files to offsite-sync manifest

Step 1 of offsite-sync-backup is incremental on non-monthly days,
driven by /mnt/backup/.changed-files which only daily-backup wrote
to. nfs-mirror's writes were therefore invisible to Step 1 until the
next monthly --delete pass — which would *also* wipe data
pre-positioned on Synology pve-backup/ (e.g. the in-place btrfs
rename we just did to relocate ~160G of NFS subtrees from
/Backup/Viki/nfs/<svc>/ to /Backup/Viki/pve-backup/<svc>/).

Fix: snapshot a timestamp before rsync, then after rsync use
`find -newer $STAMP -type f -printf '%P\n'` to enumerate every file
nfs-mirror created/modified and append to the manifest. Paths are
relative to /mnt/backup/ (matches Step 1 --files-from expectation).
State files are excluded.

The current in-flight first run started before this patch was
deployed, so its writes won't auto-populate the manifest — a one-off
manual backfill will be done after it completes.

stacks/url/providers.tf

@@ -9,6 +9,17 @@ terraform {
       source  = "cloudflare/cloudflare"
       version = "~> 4"
     }
+    authentik = {
+      source  = "goauthentik/authentik"
+      version = "~> 2024.10"
+    }
+    # kubectl (gavinbunney) — workaround for hashicorp/kubernetes
+    # `kubernetes_manifest` panics on Kyverno CRDs. See beads code-e2dp.
+    # Declared for all stacks but only used where opted-in.
+    kubectl = {
+      source  = "gavinbunney/kubectl"
+      version = "~> 1.14"
+    }
   }
 }
 
@@ -31,3 +42,8 @@ provider "vault" {
   address          = "https://vault.viktorbarzin.me"
   skip_child_token = true
 }
+
+provider "kubectl" {
+  config_path      = var.kube_config_path
+  load_config_file = true
+}