chore: merge v4.12.1 — security, calling, editor, media fixes

Key v4.12.1 changes merged:
- Security: sanitize-html updated to v2.17.4
- Calling: video calls in DMs/rooms, user avatars during calls, right-click to start
- Calling: IncomingCallListener with ring sound and answer/reject UI
- Editor: list crash fixes (Firefox + empty headings), codeblock filename support
- Media: URL preview hover state, keyboard nav, click-to-open, OGG audio support
- Date: ISO 8601 (YYYY-MM-DD) date format option
- Misc: stable mutual rooms endpoint, Android notification crash fix

Lotus customisations preserved:
- PiP drag/resize, DM call ring notification, PTT, GIF picker, noise suppression
- Poll voting, message forwarding, image captions, location sharing
- Lotus Terminal design theme

src/app/plugins/call/CallEmbed.ts

@@ -51,12 +51,36 @@ export class CallEmbed {
 
   private styleRetryObserver?: MutationObserver;
 
-  static getIntent(dm: boolean, ongoing: boolean): ElementCallIntent {
-    if (ongoing) {
-      return dm ? ElementCallIntent.JoinExistingDM : ElementCallIntent.JoinExisting;
+  static getIntent(dm: boolean, ongoing: boolean, video?: boolean): ElementCallIntent {
+    if (dm && ongoing) {
+      return video ? ElementCallIntent.JoinExistingDM : ElementCallIntent.JoinExistingDMVoice;
+    }
+    if (dm) {
+      return video ? ElementCallIntent.StartCallDM : ElementCallIntent.StartCallDMVoice;
     }
 
-    return dm ? ElementCallIntent.StartCallDM : ElementCallIntent.StartCall;
+    if (ongoing) {
+      return video ? ElementCallIntent.JoinExisting : ElementCallIntent.JoinExistingVoice;
+    }
+    return video ? ElementCallIntent.StartCall : ElementCallIntent.StartCallVoice;
+  }
+
+  static dmCall(intent: ElementCallIntent): boolean {
+    return (
+      intent === ElementCallIntent.JoinExistingDM ||
+      intent === ElementCallIntent.JoinExistingDMVoice ||
+      intent === ElementCallIntent.StartCallDM ||
+      intent === ElementCallIntent.StartCallDMVoice
+    );
+  }
+
+  static startingCall(intent: ElementCallIntent): boolean {
+    return (
+      intent === ElementCallIntent.StartCallDM ||
+      intent === ElementCallIntent.StartCallDMVoice ||
+      intent === ElementCallIntent.StartCall ||
+      intent === ElementCallIntent.StartCallVoice
+    );
   }
 
   static getWidget(
@@ -91,8 +115,13 @@ export class CallEmbed {
       noiseSuppression: noiseSuppression.toString(),
       audio: initialAudio.toString(),
       video: initialVideo.toString(),
+      header: 'none',
     });
 
+    if (!room.isCallRoom() && CallEmbed.startingCall(intent)) {
+      params.append('sendNotificationType', CallEmbed.dmCall(intent) ? 'ring' : 'notification');
+    }
+
     const widgetUrl = new URL(
       `${trimTrailingSlash(import.meta.env.BASE_URL)}/public/element-call/index.html`,
       window.location.origin