email: charset decoding, inline attachments, UI fixes

- respect charset from Content-Type when decoding body and headers
- detect inline attachments with filenames (not just disposition: attachment)
- fix broken decodeQuotedPrintable reference in parseAttachments
- white background for email iframe (emails designed for light bg)
- sticky header in email list, scrollable message area
- arrow key navigation between emails with scroll-into-view
- /email/:id routing for deep linking to specific emails
- empty folder shows "No emails in this folder" instead of losing header
- fix attachment viewer header overlap with dialog close button

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

src/apps/officer-web/Screens/Dashboard/Email/EmailScreen.tsx

@@ -1,4 +1,5 @@
-import { useMemo, useCallback } from 'react';
+import { useMemo, useCallback, useEffect } from 'react';
+import { useParams, useNavigate } from 'react-router';
 import type { LayoutNode, PanelComponents } from 'officerdev';
 import { WorkspaceView } from 'officerdev';
 import { useDashboardState } from 'state/useDashboardState';
@@ -12,7 +13,23 @@ const PROMPT_PREFIX = `You are an email assistant. The user has a local SQLite e
 
 export const EmailScreen = () => {
   const isMobile = useIsMobile();
+  const { emailId } = useParams<{ emailId?: string }>();
+  const navigate = useNavigate();
   const [selectedId, setSelectedId] = useGlobal<string | null>('EMAIL_SELECTED', null);
+
+  // Sync URL param → global state
+  useEffect(() => {
+    if (emailId && emailId !== selectedId) setSelectedId(emailId);
+  }, [emailId]);
+
+  // Sync global state → URL
+  useEffect(() => {
+    if (selectedId && selectedId !== emailId) {
+      navigate(`/email/${selectedId}`, { replace: true });
+    } else if (!selectedId && emailId) {
+      navigate('/email', { replace: true });
+    }
+  }, [selectedId]);
   const workspace = useDashboardState<LayoutNode>('screens/email', defaultLayout);
 
   const components: PanelComponents = useMemo(