feat(shutdown): implement graceful shutdown for camera session

[EthanDM]

What

Fix the navigation freeze on React Navigation/Fabric by shutting the camera session down deterministically when the view unmounts.

Changes

• Add CameraSession.shutdown, which disables photo/video/audio/code-scanner/location/torch before flipping isActive = false, and clears delegates while removing outputs.
• Stop both capture sessions asynchronously during CameraSession.deinit as a backstop.
• Have CameraView call the shutdown helper on unmount/deinit, log if teardown exceeds 2 s, and guard against concurrent shutdowns.

Tested on

• iPhone 14 Pro (iOS 26.0.1) with code scanner enabled, navigating away from the camera screen (no freeze).

Related issues

• Fixes 🐛 Navigating away on React Native 0.78+, XCode 26, and React Native Vision Camera v4.7.1 freezes the app #3636

[vercel]

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[jkaufman]

@EthanDM Thank you for your effort on this. We’ve been testing a patch that builds on yours and would appreciate a look.

[mrousavy]

Thanks for this PR - seems like there were some issues with proper session shutdown on Fabric - I wonder why that wasn't a problem before on Paper. Maybe view caching/recycling?

Anyways - I left some review comments

[EthanDM]

Thanks for the review @mrousavy, I addressed all of the comments and retested. Still no freezes during mount/unmount.

Let me know if anything else is needed.

[stanrud]

Hey guys,
We implemented the same changes in our application and began to notice periodic application crashes in the production.
Below you can find more detailed information about the crash:

Fatal Exception: NSGenericException
*** -[AVCaptureSession stopRunning] stopRunning may not be called between calls to beginConfiguration and commitConfiguration

          Fatal Exception: NSGenericException
0  CoreFoundation                 0xc5964 (Missing UUID 0be54dbe1adc3588bffae7c99e8d8208)
1  libobjc.A.dylib                0x31814 (Missing UUID ee4a4347bd733beda7149cd0b16844a2)
2  AVFCapture                     0xe16c0 (Missing UUID 758d6ce7543c309eb5693e79a971aa9b)
3  Fleetback App                  0x9d85ac CameraSession.checkIsActive(configuration:) + 297 (CameraSession.swift:297)
4  Fleetback App                  0x9d812c closure #1 in CameraSession.configure(_:completion:) + 220 (CameraSession.swift:220)
5  Fleetback App                  0x124f8 <deduplicated_symbol>
6  libdispatch.dylib              0x1adc (Missing UUID 11c047c433b339a3ae43bf617cfc7d2c)
7  libdispatch.dylib              0x1b7fc (Missing UUID 11c047c433b339a3ae43bf617cfc7d2c)
8  libdispatch.dylib              0xa468 (Missing UUID 11c047c433b339a3ae43bf617cfc7d2c)
9  libdispatch.dylib              0xaf44 (Missing UUID 11c047c433b339a3ae43bf617cfc7d2c)
10 libdispatch.dylib              0x153ec (Missing UUID 11c047c433b339a3ae43bf617cfc7d2c)
11 libdispatch.dylib              0x14ce4 (Missing UUID 11c047c433b339a3ae43bf617cfc7d2c)
12 libsystem_pthread.dylib        0x13b8 (Missing UUID 741c5afb3f30362e9313aab3de2497c9)
13 libsystem_pthread.dylib        0x8c0 (Missing UUID 741c5afb3f30362e9313aab3de2497c9)

[nakshatrasinghh]

@stanrud I think you should try this patch out!