feat(ha): implement clan vars and fully encrypt all HA secrets

- Run sync-host-keys.sh for proxmox-ha-server-{1,2}: generates SSH host
  key pairs in vars/per-machine/, registers age anchors in .sops.yaml,
  adds both hosts as recipients for common.yaml, ha-corosync-authkey,
  and per-host secrets/keytab files
- Re-encrypt secrets/common.yaml with both new host keys
- Convert all stub secrets to real sops-encrypted files:
    secrets/ha-server-{1,2}.yaml    (YAML, beszel-token = PLACEHOLDER)
    secrets/ha-server-{1,2}.keytab  (binary, stub text encrypted)
    secrets/ha-corosync-authkey      (binary, stub text encrypted)
- Add scripts/ha/deploy.sh: full lifecycle script (bridge setup, VM
  creation, DRBD disk + storage NIC attachment, boot wait, cluster-init,
  acceptance tests, --destroy)

Bootstrap order (operator runs these before first deploy):
  1. bash scripts/ha/deploy.sh            # deploys, tests
  # Post-deploy secret replacement:
  2. sops secrets/ha-server-{1,2}.yaml   (set real beszel-token)
  3. bash scripts/ipa/create-nixos-ipa-host-account.sh --ip 192.168.2.228 ha-server-1
  4. bash scripts/ipa/create-nixos-ipa-host-account.sh --ip 192.168.2.227 ha-server-2
  5. Set services.beszel.agent.environment.KEY in host.nix after hub pairing
  6. nixos-rebuild switch on both nodes to pick up real secrets

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HaH1cSGvhogRP5ExoF6nD8

.sops.yaml

@@ -22,6 +22,8 @@ keys:
   - &proxmox-pxe-boot age1ug787sgt6st6k82fgkrug2lzltw4qsukrrqqs3w27ewwqj8rg4hsxcmylz
   - &proxmox-server age1529taqdwr6t0w7cvzmty0d5y5593wffl0krt48j6uc4u39k56g2qf6ywtp
   - &proxmox-tailscale-router age1zhfyuzlq40reuqlr34gf77852nhs3t6mqfzrqmas8z6sxk7tcfhsungrm0
+  - &proxmox-ha-server-1 age1nxlnrevqs2msdatze562vz6ym4pgydt2zndye83lwqauy6flggtqrevyw5
+  - &proxmox-ha-server-2 age1scfc8p53q5aq2a87tcmsazmj8sfeft0s8kxg0et4nm3ucxyp3c3s6te82y
 
 creation_rules:
   # Shared across every currently-deployed host: root/nixos password hash,
@@ -54,6 +56,8 @@ creation_rules:
           - *proxmox-pxe-boot
           - *proxmox-server
           - *proxmox-tailscale-router
+          - *proxmox-ha-server-1
+          - *proxmox-ha-server-2
 
   - path_regex: secrets/nix-cache\.yaml$
     key_groups:
@@ -93,12 +97,14 @@ creation_rules:
     key_groups:
       - age:
           - *admin
+          - *proxmox-ha-server-1
           # proxmox-ha-server-1 added by sync-host-keys.sh
 
   - path_regex: secrets/ha-server-2\.yaml$
     key_groups:
       - age:
           - *admin
+          - *proxmox-ha-server-2
           # proxmox-ha-server-2 added by sync-host-keys.sh
 
   # Shared HA cluster corosync authkey (binary sops file).
@@ -108,6 +114,8 @@ creation_rules:
     key_groups:
       - age:
           - *admin
+          - *proxmox-ha-server-1
+          - *proxmox-ha-server-2
           # proxmox-ha-server-1 added by sync-host-keys.sh
           # proxmox-ha-server-2 added by sync-host-keys.sh
 
@@ -202,6 +210,7 @@ creation_rules:
     key_groups:
       - age:
           - *admin
+          - *proxmox-ha-server-1
           # proxmox-ha-server-1 added by sync-host-keys.sh
 
   # Host keytab for ha-server-2 FreeIPA enrollment (binary sops file).
@@ -210,4 +219,5 @@ creation_rules:
     key_groups:
       - age:
           - *admin
+          - *proxmox-ha-server-2
           # proxmox-ha-server-2 added by sync-host-keys.sh