CCExtractor

Use when auditing or updating hand-written FFmpeg constants, macro aliases, and version-gated feature flags in Rust bindings. Trigger for tasks like comparing `pixfmt.h` / `channel_layout.h` / `error.h` against `src/avutil/*.rs`, checking whether FFmpeg 8.1 added constants, determining the first FFmpeg release that introduced a symbol, or adding `ffmpegX_Y` feature gates in `Cargo.toml`.