darwin: strip embedded Python.app from Python.framework

python-build-standalone bakes a standalone launcher Python.app into
Python.framework/Versions/<ver>/Resources/. Its Mach-O has a hardcoded
load command:

  /Users/runner/work/python-build/python-build/darwin/install/macOS/
      macosx/python-3.X.Y/Python.framework/Versions/X.Y/Python

— literally the CI runner's build path. DYLD can't resolve it anywhere
else, so any attempt to launch the Python.app fails with "Library
missing". macOS LaunchServices scans nested .app bundles inside a
.app's Contents/Frameworks/ on launch (`flet debug macos`, `flet run`,
or just opening the built .app) and reliably triggers a flood of
"Python quit unexpectedly" crash report dialogs.

The launcher is only useful for standalone interpreter sessions (the
GUI Python.app you launch from /Applications); libdart_bridge dlopens
the framework's main binary directly and ignores it. Strip it after
extraction.

Existing both in 3.12 and 3.14 tarballs from flet-dev/python-build —
the previous serious_python (pub.dev 1.0.x) packaging path apparently
didn't expose it to LaunchServices, which is why it never surfaced
before the dart-bridge rewrite started routing Python.xcframework
through CocoaPods' vendored_frameworks into Contents/Frameworks/.

Author: FeodorFitsner

src/serious_python_darwin/darwin/prepare_macos.sh

@@ -29,6 +29,17 @@ if [ ! -d "$dist" ]; then
     mkdir -p "$dist"
     tar -xzf "$python_macos_dist_path" -C "$dist"
     mv "$dist/python-stdlib" "$dist/stdlib"
+
+    # python-build-standalone bakes a standalone launcher Python.app into
+    # Python.framework/Versions/<ver>/Resources/. Its Mach-O has a hardcoded
+    # load command pointing at the CI runner's build path
+    # (/Users/runner/work/python-build/.../Python.framework/Versions/X.Y/Python),
+    # so DYLD can't resolve it on any other machine. When the host .app is
+    # built, macOS LaunchServices scans nested .app bundles and tries to
+    # launch this Python.app — every scan produces a "Python quit
+    # unexpectedly" crash dialog. We don't need this launcher for embedded
+    # use; libdart_bridge dlopens Python.framework's main binary directly.
+    find "$dist/xcframeworks" -type d -name 'Python.app' -prune -exec rm -rf {} +
 fi
 
 # ---- flet-dev/dart-bridge (xcframework, same archive for macOS + iOS) -----