Generative: the video strip scrolls and reveals; tags wrap in their row

The timeline's scroll box is the flex row itself, so its reach is its
shots; a focused shot brings itself whole into view through
layout::bring_into_view, which table headers now share; Extend sits
with the caption under the strip. A voice's tags cap at the row's
width and wrap inside it.

src/generative/voice.rs

@@ -215,7 +215,9 @@ impl RenderOnce for TTSVoicePicker {
                     )
                     .child(
                         div()
+                            .debug_selector(|| format!("voice-tags-{}", voice.key))
                             .flex_none()
+                            .max_w_full()
                             .flex()
                             .flex_wrap()
                             .gap_1()