The static FFmpeg's external codec libs pull in -lz, which on this
toolchain resolves to a copy whose install name is @rpath/libz.1.dylib
(zlib-ng-compat); without an LC_RPATH entry all three binaries died in
dyld at startup. The app/cli/worker build scripts now emit
-Wl,-rpath,/usr/lib.
Also: FFMPEG_DIR moves into the committed .cargo/config.toml as a
workspace-relative [env] entry — ffmpeg-sys-next's build script cannot
read .env files, and without it the crate silently linked the shared
Homebrew FFmpeg while oakffmpeg-link emitted the static transitive
flags (mixed linkage). docs/build.md updated.
cargo test from the workspace root does not read
crates/oakcommon/.cargo/config.toml, so ocio-sys silently built its
stub bridge and oakcommon's OCIO tests failed with empty configs.
Mirror the same env (OCIO_RS_ENABLE_REAL/OCIO_INSTALL_DIR/OCIO_RS_LINK)
at the root; no manual environment variables are needed any more.
Mike-Solar