Sync export fidelity fixes + more AI providers

src/lib/screencast.ts

@@ -53,6 +53,7 @@ export interface ScreencastData {
   fps?: number;               // capture frame rate (informational)
   source?: "tab" | "window" | "screen"; // what getDisplayMedia captured (informational)
   drawCursor?: boolean;       // render the animated cursor sprite (true when the OS cursor was suppressed at capture; false = keep the real recorded cursor). default true
+  camScale?: number;          // AUTO-ZOOM INTENSITY 0..1 applied over the baked `cam` at render time (1 = full baked zoom, 0.5 = half, 0 = OFF/no zoom → shows the whole recording). Lets the user dial back an over-zoomed camera without re-capturing. default 1
 }
 
 // Resolved camera state at an instant: zoom + a translate (fractions of frame) so a