fix(core): remove 1800s hard cap on timeline duration that silently truncated long compositions (#1114)

The runtime had a maxTimelineDurationSeconds field defaulting to 1800
(30 minutes) that clamped the TransportClock duration. Any seek beyond
this cap was silently clamped, so GSAP tweens starting past ~1700s
never received their totalTime() call and stayed at their pre-tween
state (e.g. opacity:0).

The data-duration attribute is the authored source of truth. The loop-
inflation guard (timelineLooksLoopInflated) already handles the infinite
repeat:-1 case this cap was meant to protect against.

Closes #1107

packages/core/src/runtime/init.ts

@@ -538,8 +538,7 @@ export function initSandboxRuntimeModular(): void {
     } else {
       safeDuration = fallbackDuration;
     }
-    const hardDurationCap = Math.max(1, Number(state.maxTimelineDurationSeconds) || 1800);
-    return safeDuration > 0 ? Math.max(0, Math.min(safeDuration, hardDurationCap)) : 0;
+    return safeDuration > 0 ? Math.max(0, safeDuration) : 0;
   };
 
   const resolveRootTimelineFromDocument = (): TimelineResolution => {
@@ -1423,7 +1422,6 @@ export function initSandboxRuntimeModular(): void {
     bindRootTimelineIfAvailable();
     const payload = collectRuntimeTimelinePayload({
       canonicalFps: state.canonicalFps,
-      maxTimelineDurationSeconds: state.maxTimelineDurationSeconds,
     });
     window.__clipManifest = payload;
     postRuntimeMessage(payload);