Add OCR language override setting

Operators can now choose Tesseract language pack(s) per profile via a
sidebar select (#optOcrLang) and profile editor (#peOptOcrLang). Presets:
dan+eng (default), dan, eng, dan+eng+deu, dan+eng+swe, dan+eng+fra. The
ocr_lang option flows from the UI through all three scan engines (M365
files/attachments, Google Drive, Gmail) down to document_scanner.scan_pdf
and scan_image — including the spawned PDF-OCR subprocess worker.

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

lang/en.json

@@ -577,6 +577,8 @@
   "m365_badge_emails": "email",
   "m365_badge_phones": "phone",
   "m365_opt_min_cpr_hint": "Files with fewer distinct CPR numbers than this threshold are not reported. Set to 2 to avoid false positives when students have their own CPR in documents.",
+  "m365_opt_ocr_lang": "OCR language",
+  "m365_opt_ocr_lang_hint": "Tesseract language pack(s) used when scanning scanned PDFs and images. Language packs must be installed on the server (e.g. tesseract-ocr-dan). Multiple packs: dan+eng.",
   "m365_filter_photo_only": "📷 Photos / biometric",
   "m365_filter_all_roles": "All roles",
   "m365_filter_staff": "Staff",