Release v0.3.0

- New :benchmark Gradle subproject with a CLI benchmark runner for VP8/VP9 encoder and decoder throughput measurement
- SyntheticFrameSource for reproducible I420 test frames with interference waves, XOR texture, and LCG noise
- VpxEncoderConfig extended with threads, preset, cpuUsed, rowMt, tileColumns, and tokenPartitions parameters
- --synthetic flag, --help support, and strict unknown-argument handling in the benchmark CLI
- VP8 decoding and VP9 encoding/decoding examples added to README