c/Cargo.toml builds ../src/lib.rs as a shared library for main.c to link
against. It shared the real crate's name, so a cargo publish from that
directory would have targeted brotli-decompressor, and it had drifted: it
still asked for the 2.x alloc crates and never enabled ffi-api, so the library
it produced exported no BrotliDecoder symbols at all. Rename it, mark it
publish = false, mirror the root dependencies and features with the FFI on by
default, and keep the library file name the Makefile expects.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>