fix(auth): consolidate pigeon helper functions and update macOS deployment target

- Move PigeonError, wrapResult, wrapError, isNullish, and nilOrValue from WebAuthnBridge.g.swift to messages.g.swift to eliminate duplication
- Change helper function visibility from private to internal in messages.g.swift for cross-file access
- Update macOS deployment target from 10.15 to 13.5 across all build configurations
- Add development team identifier and code signing identity to Runner project
- Set product bundle identifier for example app
- Update Xcode project settings (LastUpgradeCheck, KnownAssetTags)
- Add inputPaths and outputPaths to Embed Pods Frameworks build phase
- Consolidates pigeon code generation utilities into a single source of truth

Author: Ahmed Hamouda