fix(replay): Dispatch session-deadline stop off the replay worker thread

[runningcode]

📜 Description

When a session replay reaches its duration deadline (default 1h), the resulting stop() was invoked inline from the replay worker thread, inside the add_frame task in SessionCaptureStrategy.onScreenshotRecorded. Because ReplayExecutorService.submit() runs tasks synchronously when the caller is already on a SentryReplayIntegration-* thread, stop() encoded the final video segment and recursively deleted the replay cache while holding the replay lifecycle lock (AutoClosableReentrantLock).

A foreground start() (LifecycleWatcher.onForeground → startSession) runs on the main thread and must acquire that same lock, so it parked long enough to trigger a background ANR.

This change dispatches the deadline stop() through options.executorService (a non-worker thread). stop() then submits the segment encoding asynchronously onto the single-threaded replay executor (preserving ordering), and the lifecycle lock is held only for the fast state transition — matching the existing timer-executor endSession stop path.

💡 Motivation and Context

Fixes the background ANR reported in getsentry/sentry-dart#3556 (Linear: DART-323), whose stack shows the main thread parked on the replay lifecycle lock in ReplayIntegration.start() on foreground. The deadline stop re-entering the lifecycle lock from the worker thread is the only path where the segment encode runs synchronously under the lock; every other start/stop/pause/resume caller already submits the encode asynchronously.

• GH Issue: ApplicationNotResponding sun.misc.Unsafe in park sentry-dart#3556
• Linear: DART-323

💚 How did you test it?

Added a regression test in SessionCaptureStrategyTest using a deferred executor that asserts the deadline stop() is dispatched off the calling thread (not run inline) and only runs once the executor drains. Updated the existing deadline test's fixture to use an immediate executor so it still exercises the dispatched stop.

📝 Checklist

• I added GH Issue ID & Linear ID
• I added tests to verify the changes.
• No new PII added or SDK only sends newly added PII if sendDefaultPII is enabled.
• I updated the docs if needed.
• I updated the wizard if needed.
• Review from the native team if needed.
• No breaking change or entry added to the changelog.
• No breaking change for hybrid SDKs or communicated to hybrid SDKs.

🔮 Next steps

None.

[sentry]

📲 Install Builds

Android

🔗 App Name	App ID	Version	Configuration
SDK Size	io.sentry.tests.size	8.50.0 (1)	release

⚙️ sentry-android Build Distribution Settings

[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	338.21 ms	382.47 ms	44.25 ms
Size	0 B	0 B	0 B

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
22f4345	325.23 ms	454.66 ms	129.43 ms
22f4345	312.78 ms	347.40 ms	34.62 ms
8558cac	306.16 ms	355.24 ms	49.09 ms
bb0ff41	317.76 ms	384.66 ms	66.90 ms
7c1a728	289.46 ms	368.15 ms	78.69 ms
d501a7e	314.55 ms	343.34 ms	28.79 ms
4fc476b	280.63 ms	363.04 ms	82.42 ms
6727e14	337.22 ms	373.94 ms	36.71 ms
ae7fed0	293.84 ms	380.22 ms	86.38 ms
ee747ae	400.46 ms	423.61 ms	23.15 ms

App size

Revision	Plain	With Sentry	Diff
22f4345	1.58 MiB	2.29 MiB	719.83 KiB
22f4345	1.58 MiB	2.29 MiB	719.83 KiB
8558cac	0 B	0 B	0 B
bb0ff41	0 B	0 B	0 B
7c1a728	0 B	0 B	0 B
d501a7e	0 B	0 B	0 B
4fc476b	0 B	0 B	0 B
6727e14	1.58 MiB	2.28 MiB	718.64 KiB
ae7fed0	1.58 MiB	2.12 MiB	551.77 KiB
ee747ae	1.58 MiB	2.10 MiB	530.95 KiB