feat(ui): show file owner, add claim ownership on file summary, detail, and annotations pages

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>
Agent-Logs-Url: https://github.com/christianlouis/DocuElevate/sessions/0ce1d83e-500c-473f-bbb6-ccf510ba953a

frontend/translations/en.json

@@ -1757,6 +1757,12 @@
   "sharing.role_viewer": "Viewer",
   "sharing.user_id_label": "User ID or email",
   "sharing.user_id_placeholder": "e.g. alice@example.com",
+  "file.owner_label": "Owner",
+  "file.owner_unowned": "Unowned",
+  "file.claim_ownership": "Claim Ownership",
+  "file.claim_ownership_confirm": "Claim this document as yours? You will become the owner and can manage sharing.",
+  "file.claim_ownership_success": "You are now the owner of this document.",
+  "file.claim_ownership_failed": "Could not claim ownership. The document may already have an owner.",
   "similarity.backfill_auto": "The background task will compute them automatically every 5 minutes, or you can",
   "similarity.files_missing_text": "file(s) have OCR text but no embedding yet.",
   "similarity.find_pairs_btn": "Find Pairs",