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/da.json

@@ -564,6 +564,9 @@
   "m365_opt_min_cpr": "Min. CPR-antal pr. fil",
   "m365_opt_min_cpr_hint": "Filer med færre distinkte CPR-numre end denne tærskel rapporteres ikke. Sæt til 2 for at undgå falske positive, når elever har egne CPR-numre i filer.",
   "m365_filter_photo_only": "📷 Billeder / biometrisk",
+  "m365_filter_all_roles": "Alle roller",
+  "m365_filter_staff": "Ansatte",
+  "m365_filter_student": "Elever",
   "m365_badge_faces": "ansigter",
   "a30_photo_items": "Billeder med registrerede ansigter (Art. 9 biometrisk)",
   "a30_photo_note": "Fotografier af identificerbare personer er biometriske data i henhold til Art. 9 GDPR. Opbevaring kræver et dokumenteret retsgrundlag i henhold til Art. 9(2). For skolefotografier af elever under 15 år er forældrenes samtykke påkrævet (Databeskyttelsesloven §6). Se Datatilsynets vejledning om fotografering i skoler.",