feat: add metadata refresh job to re-download metadata for linked series

Adds a new job type that refreshes metadata from external providers for
all series already linked via approved external_metadata_links. Tracks
and displays per-field diffs (series and book level), respects locked
fields, and provides a detailed change report in the job detail page.

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

apps/backoffice/lib/i18n/en.ts

@@ -173,6 +173,8 @@ const en: Record<TranslationKey, string> = {
   "jobs.generateThumbnails": "Generate thumbnails",
   "jobs.regenerateThumbnails": "Regenerate thumbnails",
   "jobs.batchMetadata": "Batch metadata",
+  "jobs.refreshMetadata": "Refresh metadata",
+  "jobs.refreshMetadataDescription": "Refreshes metadata for all series already linked to an external provider. Re-downloads information from the provider and updates series and books in the database (respecting locked fields). Series without an approved link are ignored. <strong>Requires a specific library</strong> (does not work on \"All libraries\").",
   "jobs.referenceTitle": "Job types reference",
   "jobs.rebuildDescription": "Incremental scan: detects files added, modified, or deleted since the last scan, indexes them, and generates missing thumbnails. Existing unmodified data is preserved. This is the most common and fastest action.",
   "jobs.fullRebuildDescription": "Deletes all indexed data (books, series, thumbnails) then performs a full scan from scratch. Useful if the database is out of sync or corrupted. Long and destructive operation: reading statuses and manual metadata will be lost.",
@@ -185,8 +187,7 @@ const en: Record<TranslationKey, string> = {
   "jobsList.library": "Library",
   "jobsList.type": "Type",
   "jobsList.status": "Status",
-  "jobsList.files": "Files",
-  "jobsList.thumbnails": "Thumbnails",
+  "jobsList.stats": "Stats",
   "jobsList.duration": "Duration",
   "jobsList.created": "Created",
   "jobsList.actions": "Actions",
@@ -195,6 +196,12 @@ const en: Record<TranslationKey, string> = {
   "jobRow.showProgress": "Show progress",
   "jobRow.hideProgress": "Hide progress",
   "jobRow.scanned": "{{count}} scanned",
+  "jobRow.filesIndexed": "{{count}} files indexed",
+  "jobRow.filesRemoved": "{{count}} files removed",
+  "jobRow.thumbnailsGenerated": "{{count}} thumbnails generated",
+  "jobRow.metadataProcessed": "{{count}} series processed",
+  "jobRow.metadataRefreshed": "{{count}} series refreshed",
+  "jobRow.errors": "{{count}} errors",
   "jobRow.view": "View",
 
   // Job progress
@@ -234,6 +241,14 @@ const en: Record<TranslationKey, string> = {
   "jobDetail.phase2b": "Phase 2b — Thumbnail generation",
   "jobDetail.metadataSearch": "Metadata search",
   "jobDetail.metadataSearchDesc": "Searching external providers for each series",
+  "jobDetail.metadataRefresh": "Metadata refresh",
+  "jobDetail.metadataRefreshDesc": "Re-downloading metadata from providers for already linked series",
+  "jobDetail.refreshReport": "Refresh report",
+  "jobDetail.refreshReportDesc": "{{count}} linked series processed",
+  "jobDetail.refreshed": "Refreshed",
+  "jobDetail.unchanged": "Unchanged",
+  "jobDetail.refreshChanges": "Changes detail",
+  "jobDetail.refreshChangesDesc": "{{count}} series with changes",
   "jobDetail.phase1Desc": "Scanning and indexing library files",
   "jobDetail.phase2aDesc": "Extracting the first page of each archive (page count + raw image)",
   "jobDetail.phase2bDesc": "Generating thumbnails for scanned books",
@@ -273,6 +288,7 @@ const en: Record<TranslationKey, string> = {
   "jobType.thumbnail_regenerate": "Regen. thumbnails",
   "jobType.cbr_to_cbz": "CBR → CBZ",
   "jobType.metadata_batch": "Batch metadata",
+  "jobType.metadata_refresh": "Refresh meta.",
   "jobType.rebuildLabel": "Incremental indexing",
   "jobType.rebuildDesc": "Scans new/modified files, analyzes them, and generates missing thumbnails.",
   "jobType.full_rebuildLabel": "Full reindexing",
@@ -285,6 +301,8 @@ const en: Record<TranslationKey, string> = {
   "jobType.cbr_to_cbzDesc": "Converts a CBR archive to the open CBZ format.",
   "jobType.metadata_batchLabel": "Batch metadata",
   "jobType.metadata_batchDesc": "Searches external metadata providers for all series in the library and automatically applies 100% confidence matches.",
+  "jobType.metadata_refreshLabel": "Metadata refresh",
+  "jobType.metadata_refreshDesc": "Re-downloads and updates metadata for all series already linked to an external provider.",
 
   // Status badges
   "statusBadge.extracting_pages": "Extracting pages",