T25d Generative: sound and motion

AudioGenerationPlayer shows a generated sound's prompt, model and
length, a bar while it is made, then chat::AudioMessage to play it;
Regenerate and Download wait for it. TTSVoicePicker lists voices with a
sample to play, the chosen one washed with a check, tags dropping below
when narrow. VideoGenerationTimeline lays shots along their time under
a ruler, with posters, placeholders, a playhead and Extend.

AudioMessage's waveform is one Tab stop where Left and Right seek, and
it gives way at 280px. debug::ruler serves the timeline's ruler. A mask
shown to read no longer follows the pointer.

src/generative/mod.rs

@@ -1,3 +1,4 @@
+mod audio;
 mod brush;
 mod compare;
 mod grid;
@@ -10,7 +11,10 @@ mod style;
 #[cfg(all(test, feature = "test-support"))]
 mod tests;
 mod variation;
+mod video;
+mod voice;
 
+pub use audio::AudioGenerationPlayer;
 pub use brush::MaskBrush;
 pub use compare::{ABCompareView, Verdict};
 pub use grid::{GenerationGrid, Outcome};
@@ -21,3 +25,5 @@ pub use ratio::AspectRatioPicker;
 pub use seed::SeedInput;
 pub use style::{StylePreset, StylePresetPicker};
 pub use variation::VariationPicker;
+pub use video::{Shot, VideoGenerationTimeline};
+pub use voice::{TTSVoicePicker, Voice};