test: Add failing harness tests for AE resetting to max ISO on session start

[stevengoldberg]

What

Adds two failing harness tests to visioncamera.controller.harness.ts reproducing a v5 regression: every CameraSession.start() resets auto-exposure to the format's max ISO, so the first ~600–900 ms of preview are massively overexposed while AE visibly ramps back down. v4 and the native camera app show correctly exposed frames immediately.

The two tests

1. keeps an exposure lock applied between configure() and start() — deterministic and scene-independent. Locks exposure to a mid-range ISO / short duration after configure() but before start(), then asserts the lock survives start(). Today start() clobbers the lock: exposureMode resets to continuous auto-exposure and iso jumps to the format's max.

2. resumes auto-exposure near previously converged values on a fresh session — the user-facing symptom. Lets AE converge in a first session, stops it, starts a second session on the same device, and asserts the first readable ISO is within 4x of the converged value. Today the second session restarts at max ISO (~50x above a typical indoor converged value). The test skips itself when the scene is so dark that converged ISO is near max (e.g. taped-over Device Farm cameras), since the regression would be indistinguishable from correct convergence there.

Observed telemetry (iPhone, indoor scene, RNVC 5.0.11)

[AE] session started
[AE] iso=5184 shutter=1/24 bias=0 mode=continuousAutoExposure   <- max ISO for the format
[AE] iso=1280 shutter=1/30 bias=0 mode=continuousAutoExposure
[AE] iso=920  shutter=1/30 bias=0 mode=continuousAutoExposure
[AE] iso=482  shutter=1/30 bias=0 mode=continuousAutoExposure
[AE] iso=296  shutter=1/35 bias=0 mode=continuousAutoExposure
[AE] iso=108  shutter=1/91 bias=0 mode=continuousAutoExposure   <- converged after ~700ms

This happens on every start(), including when the AVCaptureDevice still holds the previously converged exposure values, and even when an explicit setExposureLocked(...) was applied between configure() and start().

Expected

start() should leave the device's exposure state alone (or at minimum honor an explicit lock), matching v4 and AVCaptureSession behavior in a plain native app, where the first rendered frames are already correctly exposed.

[vercel]

@stevengoldberg is attempting to deploy a commit to the Margelo Team on Vercel.

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[mrousavy]

Thanks! PR triggered