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/debug/mod.rs

@@ -19,6 +19,7 @@ pub use hex::HexViewer;
 pub use network::{NetworkInspector, Request};
 pub use session::{Breakpoint, BreakpointList, DebugCommand, DebugState, DebugToolbar};
 pub use stack::{CallStack, StackFrame, Thread, ThreadList, ThreadState};
+pub(crate) use timeline::ruler;
 pub use timeline::{Span, TimelineProfiler, zoomed};
 pub use variables::{ValueKind, Variable, VariablesPanel, Watch, WatchPanel};
 

src/debug/timeline.rs

@@ -35,7 +35,7 @@ fn tick_label(time: f64, step: f64) -> String {
 const TICKS: usize = 6;
 
 /// The ruler's step and ticks: as many as leave `room` for each label across `width`, each with room before the end.
-fn ruler(range: (f64, f64), width: f32, room: f32) -> (f64, Vec<f64>) {
+pub(crate) fn ruler(range: (f64, f64), width: f32, room: f32) -> (f64, Vec<f64>) {
     let length = range.1 - range.0;
     let across = move |span: f64| (span / length) as f32 * width;
     let step = (2..=TICKS)