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>

docs/manuals/MANUAL-EN.md

@@ -226,6 +226,7 @@ Use the filter bar above the results to narrow down what you see:
 - **Disposition dropdown** — show items by their review status.
 - **Transfer dropdown** — filter by shared / external / all.
 - **Risk dropdown** — show only Art. 9, photos, GPS, or high-risk items.
+- **Role dropdown** — show only **Ansatte** (staff) or **Elever** (students). Also scopes exports: clicking **Excel** or **Art.30** while a role is selected produces a report containing only that group, with `_elever` or `_ansatte` appended to the filename.
 
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