fix(packaging): resolve the packaged speakers-analyze helper's ONNX Runtime by target OS master
The published 1.0.18 macOS helper carried the Linux $ORIGIN runtime token, which dyld rejects in a hardened program, so the helper aborted at launch instead of finding the bundled ONNX Runtime dylib. Emit the helper rpath from CARGO_CFG_TARGET_OS so Linux keeps its byte-identical $ORIGIN RUNPATH and macOS bakes @loader_path/../lib/solstone-core-speakers-analyze before signing. Add a speakers-analyze-specific Mach-O load-command check that requires LC_RPATH plus LC_LOAD_DYLIB @rpath/libonnxruntime.1.25.0.dylib, and add fixture coverage that rejects the shipped $ORIGIN value while accepting the @loader_path value. The Darwin link itself is not exercisable on this Linux host; it is proven by the calling session's pro5e build. This commit does not bump versions or add publish, tag, transparency, or retained-ledger schema behavior.