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>

templates/index.html

@@ -361,6 +361,11 @@ document.addEventListener('DOMContentLoaded', applyI18n);
             <option value="1" data-i18n="m365_filter_special_only">⚠ Art. 9 only</option>
             <option value="photo" data-i18n="m365_filter_photo_only">📷 Photos / biometric</option>
           </select>
+          <select id="filterRole" onchange="applyFilters()" style="width:120px">
+            <option value="" data-i18n="m365_filter_all_roles">All roles</option>
+            <option value="staff" data-i18n="m365_filter_staff">Ansatte</option>
+            <option value="student" data-i18n="m365_filter_student">Elever</option>
+          </select>
           <button class="filter-clear" onclick="clearFilters()" data-i18n="m365_filter_clear">Ryd</button>
           <div class="spacer"></div>
           <button id="exportBtn" onclick="exportExcel()" style="background:none;border:1px solid var(--border);color:var(--muted)" data-i18n="m365_btn_export_excel" title="Export results as Excel">Excel</button>