feat(presets): add isProgramUser field to PresetCall schema (#213)

Allows presets to store whether a program output line is joined as a
listener or as an audio feed, enabling full role-aware auto-join when
loading a preset URL.

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: LucasMaupin

src/models.ts

@@ -405,6 +405,7 @@ export const PresetCall = Type.Object({
   productionId: Type.String({ minLength: 1 }),
   lineId: Type.String({ minLength: 1 }),
   lineUsedForProgramOutput: Type.Optional(Type.Boolean()),
+  isProgramUser: Type.Optional(Type.Boolean()),
   lineName: Type.Optional(Type.String())
 });