feat: scan history browser, user-scoped viewer tokens, export fixes, email fixes (v1.6.20)

- Scan history browser (history.js, GET /api/db/sessions, get_sessions(),
  get_session_items(ref_scan_id)) — review any past session without rescanning
- User-scoped viewer tokens (#34) — scope by individual employee across M365
  and GWS; autocomplete from Accounts list; dual-email support
- Fix: GWS scan never marked finished (end_scan → finish_scan) and emitted
  wrong SSE event (scan_done → google_scan_done), excluding GWS items from all
  exports
- Fix: file scan begin_scan called with wrong keyword args (TypeError swallowed),
  so local/SMB items were never written to DB
- Fix: Graph sendMail reported failure on success — _post() now returns {} on
  empty 202 response instead of raising JSONDecodeError
- Fix: Graph error hidden behind generic "No SMTP host" message when both Graph
  and SMTP were unavailable
- Fix: Gmail vs Google Workspace SMTP error messages distinguished by username
  domain; Workspace errors point to admin console, not personal security settings
- Docs: update README, MANUAL-EN, MANUAL-DA, CLAUDE.md, TODO.md, CHANGELOG.md

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

static/js/scan.js

@@ -399,6 +399,7 @@ function _attachScanListeners(source) {
     if (d.delta) checkDeltaStatus();
     markOverdueCards();
     loadTrend();
+    window.invalidateHistoryCache?.();
   });
   source.addEventListener('google_scan_done', function(e) {
     var d = JSON.parse(e.data);
@@ -427,6 +428,7 @@ function _attachScanListeners(source) {
     log('Google scan complete \u2014 ' + d.flagged_count + ' flagged of ' + d.total_scanned, 'ok');
     markOverdueCards();
     loadTrend();
+    window.invalidateHistoryCache?.();
   });
   source.addEventListener('file_scan_done', function(e) {
     var d = JSON.parse(e.data);
@@ -452,9 +454,10 @@ function _attachScanListeners(source) {
         applyFilters();
       }
     }
-    log('Bestandsscan fuldført \u2014 ' + d.flagged_count + ' flagget af ' + d.total_scanned, 'ok');
+    log('Bestandsscan fuldf\u00f8rt \u2014 ' + d.flagged_count + ' flagget af ' + d.total_scanned, 'ok');
     markOverdueCards();
     loadTrend();
+    window.invalidateHistoryCache?.();
   });
   // sse_replay_done marks end of buffer replay — log a note so the user knows
   // earlier events above were replayed from an already-running scan
@@ -520,6 +523,8 @@ function startScan(resume) {
     document.getElementById('statsSection').style.display = 'none';
     document.getElementById('statsPill').style.display = 'none';
   }
+  // Exit history mode — live SSE takes over
+  window.exitHistoryMode?.();
   document.getElementById('resumeBanner').style.display = 'none';
   document.getElementById('logPanel').innerHTML = '<div class="log-line log-live" id="logLive" style="display:none"></div>';
   try { sessionStorage.removeItem(_LOG_SESSION_KEY); } catch(e) {}