feat(console): remove deprecated SPICE support in favor of noVNC

- Remove obsolete spice-html5 static assets and SPICE console templates
- Restrict default console types to VNC with migration 0012
- Filter out SPICE in VM creation form and backend capabilities
- Return friendly deprecation notice if legacy VM is opened with SPICE
- Clean up docs, architecture references, and libvirt-bootstrap scripts

appsettings/migrations/0012_remove_spice_qemu_console_type.py

@@ -0,0 +1,38 @@
+from django.db import migrations
+
+
+def update_console_type(apps, schema_editor):
+    AppSettings = apps.get_model("appsettings", "AppSettings")
+    db_alias = schema_editor.connection.alias
+    setting = (
+        AppSettings.objects.using(db_alias)
+        .filter(key="QEMU_CONSOLE_DEFAULT_TYPE")
+        .first()
+    )
+    if setting:
+        setting.value = "vnc"
+        setting.choices = "vnc"
+        setting.save(using=db_alias)
+
+
+def reverse_console_type(apps, schema_editor):
+    AppSettings = apps.get_model("appsettings", "AppSettings")
+    db_alias = schema_editor.connection.alias
+    setting = (
+        AppSettings.objects.using(db_alias)
+        .filter(key="QEMU_CONSOLE_DEFAULT_TYPE")
+        .first()
+    )
+    if setting:
+        setting.choices = "vnc,spice"
+        setting.save(using=db_alias)
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("appsettings", "0011_alter_appsettings_id"),
+    ]
+
+    operations = [
+        migrations.RunPython(update_console_type, reverse_console_type),
+    ]