* Update iOS icons and app name for staging
* fix(ios): harden build script and correct Release display name
- Add cargo check to environment validation in build_ios.sh
- Add existence check before cd rust to give informative errors
- Replace fragile cd/pod install/cd with pushd/popd and error handling
- Add POSIX-compliant trailing newline to build_ios.sh
- Fix project-level Release APP_DISPLAY_NAME ("White Noise staging" → "White Noise") to match target-level value
* feat(android): add staging flavor launcher icons
Add ic_launcher_foreground, ic_launcher_background, ic_launcher_monochrome,
and legacy ic_launcher PNGs for all densities (mdpi through xxxhdpi) plus
the mipmap-anydpi-v26 adaptive icon XML in the staging source set.
* fix(ios): add CocoaPods availability check to build script
* chore: replace LICENSE copies with symlinks to root
Fixes missing license warnings during iOS builds by ensuring
rust/ and rust_builder/ both symlink to the root LICENSE file.
Please ignore this folder, which is just glue to build Rust with Flutter.