Add sanoid Ansible role for ZFS snapshots and replication

Replaces manually deployed config files with a fully idempotent role:
installs sanoid, templates sanoid.conf and syncoid service/timer from
variables, enables both systemd timers. Removes static proxmox/sanoid.*
files. README rebuild section updated accordingly.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

ansible/roles/sanoid/defaults/main.yml

@@ -0,0 +1,37 @@
+---
+sanoid_datasets:
+  - dataset: rpool/data
+    template: vms
+    recursive: true
+  - dataset: rpool/ROOT
+    template: system
+    recursive: true
+
+sanoid_templates:
+  vms:
+    daily: 7
+    weekly: 4
+    monthly: 0
+    hourly: 0
+    frequently: 0
+    autosnap: true
+    autoprune: true
+  system:
+    daily: 3
+    weekly: 2
+    monthly: 0
+    hourly: 0
+    frequently: 0
+    autosnap: true
+    autoprune: true
+
+syncoid_jobs:
+  - src: rpool/data
+    dst: hdd/backups/rpool-data
+    recursive: true
+  - src: rpool/ROOT/pve-1
+    dst: hdd/backups/pve-root
+    recursive: false
+
+syncoid_schedule: "*-*-* 02:00:00"
+syncoid_randomized_delay: 10min