fix(backup): use complete messages for archives and destinations

AppImage/messages/README.md

@@ -7,4 +7,22 @@ The ProxMenux Monitor dashboard uses a small client-side i18n layer.
 
 To improve a translation, edit the values in your locale's `common.json` — keep placeholders such as `{uptime}`, `{vmid}` or `{count}` unchanged, and don't translate brand or product names (`ProxMenux Monitor`, `Proxmox Backup Server`, `Secure Gateway`, `Tailscale`, etc.). Missing keys fall back to English at runtime, so a partial refresh is always safe to merge.
 
+## Backup message composition regressions
+
+From the repository root, run:
+
+```sh
+node tests/test_backup_archives_empty.cjs
+node tests/test_backup_destination_messages.cjs
+```
+
+Prerequisites: Node.js and the `typescript` development dependency from
+`AppImage/package.json` must be installed/resolvable (normally in
+`AppImage/node_modules`). These tests compile actual JSX message branches and
+pure i18n lookup functions without importing the component or calling a backend.
+They cover whole English messages, missing-key locale fallback, loading/error
+branches, nonempty lists, the removal notice at zero/one/multiple archives,
+local-attach help, and unchanged shared labels. They do not replace browser or
+real-host acceptance. Keep literal paths in the local-attach help unchanged.
+
 To add a new locale, see [§11 → Adding a new locale](../../CONTRIBUTING.md#adding-a-new-locale) in the Contributing Guide.

AppImage/messages/en/common.json

@@ -3828,6 +3828,7 @@
       "downloadTitle": "Download this backup",
       "emptyAfter": "backups yet.",
       "emptyBefore": "No",
+      "emptyMessage": "No backup archives found.",
       "encrypted": "Encrypted",
       "encryptedTitle": "This backup is encrypted",
       "filesInBackup": "Files in backup",
@@ -3903,6 +3904,7 @@
       "addPbsRepository": "Add PBS repository",
       "appendAuthorizedKeyBefore": "Append the generated public key to",
       "backupsKeptBefore": "Existing backups are kept in",
+      "backupsKeptMessage": "Existing backup archives are not deleted.",
       "borgEncryptionInherited": "Borg encryption is controlled by the repository.",
       "builtIn": "Built-in",
       "builtInDefault": "Built-in default",
@@ -3923,6 +3925,7 @@
       "leavePassphraseBlank": "Leave blank to keep the saved passphrase.",
       "leavePasswordBlank": "Leave blank to keep the saved password.",
       "localAttachHelpBefore": "Use a mounted local path. For USB drives, mount them first in",
+      "localAttachHelpMessage": "Mount USB drives first. Leave blank to use the PVE storage path + /dump (fallback: /var/lib/vz/dump).",
       "localAttachHelpMiddle": "USB drives",
       "localManualPickHelp": "Pick a local path for one-shot backup output.",
       "localPathHelpAfter": "or another mounted path.",