v1.4.0 — embedded caption text-size scaling

Added

• Embedded caption text-size scaling (#43): NativeVideoPlayerSubtitleStyle.embeddedTextScale (default 1.0 = platform default) and the convenience method controller.setNativeSubtitleTextScale(double) scale the text size of EMBEDDED (native-rendered) subtitle tracks — ExoPlayer's SubtitleView on Android (both the lightweight and PlayerView display paths), AVPlayerItem.textStyleRules on iOS. Takes effect live without a playback restart, survives quality/audio/variant switches, item reloads, and native view recreation, and scales relative to the user's system caption size preference. Sidecar overlay sizing (subtitleStyle.fontSize) is unaffected.