Opt-in rotation of portrait video onto the process canvas

[kalwalt]

Summary

Closes/relates to #344.

CameraViewRenderer.prepareImage() fits the camera stream into a fixed 320x240 (4:3) process canvas. For a portrait stream this letterboxes it heavily, leaving the NFT tracker much less usable width and pushing markers below the tracking.c 3-point floor sooner than in landscape. This was measured and reported in #344 (~2.3x more tracking points when rotating the frame instead of letterboxing it).

This adds an opt-in videoSettings.rotatePortrait flag (default false, no behavior change unless set). When enabled and the stream is portrait (vh > vw):

• CameraViewRenderer rotates the frame 90 degrees onto the process canvas instead of letterboxing it (destination footprint is identical to the non-rotated case, only the source draw is rotated).
• NFTWorker rotates the projection matrix back so the AR content isn't rendered rotated 90 degrees relative to the (correctly oriented, untouched) visible video.
• NFTWorker now receives the actual runtime video dimensions from CameraViewRenderer (previously it received the requested config width/height, which isn't guaranteed to match what the device actually negotiated).

The shared canvas-fitting math (previously duplicated between CameraViewRenderer.prepareImage() and ARnftUtils.getWindowSize()) is now a single getProcessGeometry() helper, so both stay in sync going forward.

Caveat — please verify on-device

The rotation-direction math for the projection matrix compensation was derived from the canvas transform used here (not copy-pasted from the reporter's own patch, which has a different pipeline), and verified with tsc/prettier, but not verified end-to-end on a real portrait camera stream with an NFT marker — I don't have a device to test with. If the AR content comes out rotated the wrong way on-device, the fix is a one-line sign flip in NFTWorker.ts/NFTWorker.simd.ts, in the if (rot) { ... } block:

- proj[4 * c] = y;
- proj[4 * c + 1] = -x;
+ proj[4 * c] = -y;
+ proj[4 * c + 1] = x;

Test plan

• tsc --noEmit passes
• prettier --check passes on changed files
• Default (flag off) path verified to produce numerically identical geometry to the pre-existing code
• On-device test with a portrait camera stream + NFT marker (rotation direction, tracking improvement)
• Confirm landscape behavior is unaffected on a real device

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