ci(shorebird): use framework.zip as macos-framework src (xcframework, not single-arch) (#151)

create_macos_framework.py with --zip produces two outputs in dst/:
- FlutterMacOS.framework.zip — single-arch, double-zipped framework
  (~17 MB)
- framework.zip — the xcframework (both arm64 + x64) plus codesign
  config files (entitlements.txt, without_entitlements.txt,
  unsigned_binaries.txt) (~122 MB)

Legacy mac_upload.sh uploads framework.zip (the xcframework). Compose
was uploading the single-arch FlutterMacOS.framework.zip and renaming
it to framework.zip in the bucket via the dst path — same name on
disk, completely different bytes.

Verified by bucket-comparing engine 93865d6 (sharded, post-#150)
against legacy 25c9b21 at the same darwin-x64-release/framework.zip
path: 17,237,143 bytes vs 121,918,469 bytes. After this lands, the
sharded artifact at that path should be the xcframework matching
legacy in size and contents.

Author: eseidel

shorebird/ci/compose.json

@@ -22,7 +22,7 @@
       "--x64-out-dir": "mac_release"
     },
     "artifacts": [
-      {"src": "FlutterMacOS.framework.zip", "dst": "flutter_infra_release/flutter/$engine/darwin-x64-release/framework.zip"},
+      {"src": "framework.zip", "dst": "flutter_infra_release/flutter/$engine/darwin-x64-release/framework.zip"},
       {"src": "FlutterMacOS.framework.dSYM.zip", "dst": "flutter_infra_release/flutter/$engine/darwin-x64/FlutterMacOS.framework.dSYM.zip"}
     ]
   },