mediaencode-ffmpeg 0.19.0

The FFmpeg write adapter of the mediaio family. In this release: the encoder-by-name catalogue, with GPL encoders reachable only behind the `gpl` feature and refused by name without it.
# Changelog

All notable changes to the [`mediaencode-ffmpeg`](https://crates.io/crates/mediaencode-ffmpeg)
crate are documented in this file.

The format follows [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
and this crate adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
The family releases in lockstep.

## [0.19.0] - 2026-10-16

### Added

- **The encoder-by-name catalogue**, the gate every FFmpeg encoder will
  be opened through: `lookup` checks a closed catalogue and the license
  gate without asking FFmpeg anything, and `encoder_by_name` then asks
  the linked libavcodec, answering an `Admitted` encoder or an
  `EncoderRefusal` by name.
- **The `gpl` feature, off by default.** Without it the GPL encoders
  (`libx264`, `libx264rgb`, `libx265`) are refused by name before
  libavcodec is asked for them. Linking a GPL FFmpeg makes a binary GPL
  whatever this feature says; the README states it.
- The muxer and the encoders arrive in the following releases.