Replace hardcoded English strings in 32 Dart source files with l10n
references. Covers settings labels, UI actions, map/SAR features,
device config, notifications, profiles, spectrum scan, and status
messages for sl, de, hr, pl, es, fr, it, el, ru, tr, uk, zh, pt.
- Updated voice support to only include iOS, removing MacOS support.
- Added Greek (el) to the list of supported locales in LocalePreferences.
- Enhanced localization strings for Greek language.
- Modified Podfile to exclude C source files from the macOS build of codec2_flutter, as voice messages are iOS-only.