feat: remove storage-level PBS prune, keep retention in PBS

playbooks/pve-storage-pbs.yml: drop the prune-backups policy from the PVE
storage entry `pbs` so retention authority lives only in the PBS prune job
(prune-pbs). The weekly local PBS-container backup on storage `backup`
(keep-last=2) is an intentional exception and left alone.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012uoq5AVK8mkBgg83Mq6o5V

ansible/playbooks/pve-storage-pbs.yml

@@ -0,0 +1,70 @@
+---
+- name: Remove storage-level PBS prune policy from pbs storage
+  hosts: mini-pc
+  gather_facts: false
+  tasks:
+    - name: Read current PBS storage configuration
+      ansible.builtin.command:
+        argv:
+          - pvesh
+          - get
+          - /storage/pbs
+          - --output-format
+          - json
+      register: pbs_storage_current_raw
+      changed_when: false
+      no_log: true
+
+    - name: Parse current PBS storage configuration
+      ansible.builtin.set_fact:
+        pbs_storage_current: "{{ pbs_storage_current_raw.stdout | from_json }}"
+      no_log: true
+
+    - name: Assert current PBS storage is safe to modify
+      ansible.builtin.assert:
+        that:
+          - pbs_storage_current.storage | default('') == 'pbs'
+          - pbs_storage_current.type | default('') == 'pbs'
+          - pbs_storage_current.digest | default('') | length > 0
+        fail_msg: Refusing to modify /storage/pbs because the returned storage metadata is unexpected or missing a digest.
+      no_log: true
+
+    - name: Remove storage-level prune policy from PBS storage
+      ansible.builtin.command:
+        argv:
+          - pvesh
+          - set
+          - /storage/pbs
+          - --delete
+          - prune-backups
+          - --digest
+          - "{{ pbs_storage_current.digest }}"
+      when: pbs_storage_current.get('prune-backups') is not none
+      changed_when: true
+      no_log: true
+
+    - name: Read back PBS storage configuration
+      ansible.builtin.command:
+        argv:
+          - pvesh
+          - get
+          - /storage/pbs
+          - --output-format
+          - json
+      register: pbs_storage_after_raw
+      changed_when: false
+      no_log: true
+
+    - name: Parse read-back PBS storage configuration
+      ansible.builtin.set_fact:
+        pbs_storage_after: "{{ pbs_storage_after_raw.stdout | from_json }}"
+      no_log: true
+
+    - name: Assert storage-level prune policy is absent
+      ansible.builtin.assert:
+        that:
+          - pbs_storage_after.storage | default('') == 'pbs'
+          - pbs_storage_after.type | default('') == 'pbs'
+          - pbs_storage_after.get('prune-backups') is none
+        fail_msg: Storage-level prune policy still exists on /storage/pbs after the declarative fix.
+      no_log: true