fix(files): close preview on navigation/delete/rename + backfill i18n (#150)

* i18n: backfill files/download translations for de, es, fr, ja, ko, pt

Add nav.files, files.* (39 keys), and download.* (9 keys) so the file
browser UI is fully localized in these six locales instead of falling
back to English.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* fix(files): close preview when navigating or affected file changes

Opening a preview and then navigating directories, deleting the
previewed file, or renaming it left the preview pane stuck on stale
content because previewFile was never cleared.

- stores/hermes/files.ts:
  - fetchEntries clears previewFile on path change (in-place refresh
    keeps the preview).
  - deleteEntry / renameEntry clear preview/editor state when the
    affected entry matches the previewed/edited file or its parent.
  - Add isAffected(target, changed, isDir) helper.
- components/hermes/files/FilePreview.vue: replace the misleading
  common.cancel close button with a dedicated files.closePreview key
  plus an X icon and quaternary style.
- i18n: add files.closePreview to all 8 locales.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

packages/client/src/i18n/locales/en.ts

@@ -595,6 +595,7 @@ export default {
     backendError: 'File operation failed',
     dragDropHint: 'Drag files here to upload',
     closeEditor: 'Close Editor',
+    closePreview: 'Close',
     saveFile: 'Save',
   },
   // Download