feat: role filter in results grid + role-scoped Excel and Art.30 exports

- New Role dropdown in filter bar (All / Ansatte / Elever) — filters the
  results grid client-side via applyFilters() and clearFilters().

- Exports respect the active role: exportExcel() and exportArticle30()
  append ?role=student|staff to the fetch URL when a role is selected.

- _build_excel_bytes(role='') and _build_article30_docx(role='') filter
  to a local _items list at the top; all internal sheets (Summary, GPS,
  External transfers, Art.30 staff/student tables) see only the filtered
  subset. Filenames get _elever or _ansatte suffix.

- i18n: m365_filter_all_roles / m365_filter_staff / m365_filter_student
  added to en/da/de.json.

- CLAUDE.md, README.md, CHANGELOG.md, MANUAL-EN.md, MANUAL-DA.md updated.

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

lang/en.json

@@ -564,6 +564,9 @@
   "m365_opt_min_cpr": "Min. CPR count per file",
   "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_filter_photo_only": "📷 Photos / biometric",
+  "m365_filter_all_roles": "All roles",
+  "m365_filter_staff": "Staff",
+  "m365_filter_student": "Students",
   "m365_badge_faces": "faces",
   "a30_photo_items": "Photos with detected faces (Art. 9 biometric)",
   "a30_photo_note": "Photographs of identifiable persons are biometric data under Art. 9 GDPR. Retention requires a documented legal basis under Art. 9(2). For school photographs of pupils under 15, parental consent is required (Databeskyttelsesloven §6). See Datatilsynet guidance on school photography.",