Script pane, realtime peer sync, and logout button

- Script pane: PDF tab beside annotations; "Add script annotation" arms
  highlight mode on the draft, ✓/✕ to confirm/cancel, auto-scrolls to the
  active annotation's highlights during playback. Adds Project.script.
- Realtime: Django Channels websocket per project broadcasts attributed
  scene deltas after each save; peers merge them in (keeping local drafts).
- Logout link in the editor project-bar.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

scenes/migrations/0006_project_script.py

@@ -0,0 +1,18 @@
+# Generated by Django 6.0.6 on 2026-06-29 08:07
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('scenes', '0005_project_thumbnail_error_project_thumbnail_manifest_and_more'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='project',
+            name='script',
+            field=models.FileField(blank=True, null=True, upload_to='scripts/'),
+        ),
+    ]