fix(android): prevent encoder & reverse-render crashes

[hm21]

Summary

Fixes several crash sources in the Android render pipeline, including a RENDER_ERROR codec exception on Qualcomm AVC hardware encoders and potential crashes in the reverse-video pre-render path.

The original failure:

PlatformException(RENDER_ERROR, Codec exception: CodecInfo{type=VideoEncoder, ...
mime=video/avc, bitrate=8739850, bitrate-mode=1, profile=8, level=16384, ...
name=c2.qti.avc.encoder}, ...)

Changes

Main render path

• Enable encoder fallback (DefaultEncoderFactory.Builder.setEnableFallback(true)) so Media3 falls back to supported encoder settings instead of failing the whole render when the hardware encoder rejects the requested configuration.

applyBitrate

• Clamp the requested bitrate into the codec's supported range instead of bailing out (which previously left the encoder on its very high default bitrate — one of the configurations Qualcomm encoders reject).
• Prefer VBR over CBR when the bitrate sits in the upper portion of the supported range, since high-bitrate CBR is the combination most frequently rejected by hardware encoders.

VideoReverser (reverse pre-render)

• Configure the all-intra encoder with a clamped bitrate and progressive fallback (preferred → w·h·4 → w·h·2), wrapped in try/catch, to avoid a MediaCodec.CodecException crashing the reverse thread (e.g. when an HEVC source bitrate is invalid for AVC).
• Guard remuxReversed against OutOfMemoryError: the all-intra temp file is loaded fully into RAM, so its size is checked against available heap (with a 2× margin) before loading. Oversized segments throw a clear exception instead of killing the process.

Both reverse-path exceptions are caught by the existing fallback in preReverseClips, so the clip gracefully degrades to forward playback rather than failing the entire render.

Testing

• Android render verified to compile (no analyzer errors).
• Recommend testing render + reverse render on a Qualcomm/Snapdragon device with high-bitrate 1080p and long/4K clips.