Reject empty recording downloads and store WebM with correct MIME.

Mark legacy zero-byte placeholders as failed, validate files on show/download, and surface upload errors in the meeting room.

Co-authored-by: Cursor <cursoragent@cursor.com>

resources/js/meet-room.js

@@ -800,7 +800,12 @@ function meetRoom() {
             const recordingUuid = data.recording_uuid || this.activeRecordingUuid;
 
             if (blob && recordingUuid) {
-                await this.uploadRecording(blob, recordingUuid);
+                const uploaded = await this.uploadRecording(blob, recordingUuid);
+                if (!uploaded) {
+                    window.alert('Recording upload failed. Open Recordings and try again, or re-record the meeting.');
+                }
+            } else if (recordingUuid) {
+                window.alert('No recording was captured from this meeting. Start recording again while the meeting is live.');
             }
 
             this.activeRecordingUuid = null;
@@ -834,11 +839,13 @@ function meetRoom() {
             const form = new FormData();
             form.append('recording', blob, `${recordingUuid}.webm`);
 
-            await fetch(`/room/${this.config.sessionUuid}/recordings/${recordingUuid}/upload`, {
+            const res = await fetch(`/room/${this.config.sessionUuid}/recordings/${recordingUuid}/upload`, {
                 method: 'POST',
                 headers: { 'X-CSRF-TOKEN': this.config.csrf, Accept: 'application/json' },
                 body: form,
             });
+
+            return res.ok;
         },
 
         async toggleLock() {