Capture · Roots: roots drop w_full; hosts give the width

145 component roots drop w_full, the early returns included. Three
field rows keep it, Input, InputGroup and TagInput: stretched without
a width, taffy 0.9 laid the field's flex_1 share at no width in the
template picker at 280px, and the placeholder drew nothing. Container
keeps it, since mx_auto needs a width to fill.

Hosts that relied on a root's width now give it: MessageList boxes
each row at the list's width, the splash gives its bar the column's,
and test stages that mount a component as the window's root sit in a
size_full box. Tests hold a narrow row across the list and the splash
bar across its column; each goes red without its fix.

The gallery gains --narrow <px>, which lays each page in a padded
card at that width and shoots it without its script. The page
header wraps: the title takes the room and the theme switcher drops
below, where a long summary used to push it past the edge. A file
panel step waits for the panel to become key instead of a fixed
pause, which lost a race in a capture.

src/media/annotate.rs

@@ -428,7 +428,6 @@ impl RenderOnce for ImageAnnotator {
                 })
         });
         div()
-            .w_full()
             .flex()
             .flex_col()
             .gap_3()

src/media/audio.rs

@@ -145,7 +145,6 @@ impl RenderOnce for AudioWaveform {
             .id(self.id.clone())
             .debug_selector(|| "audio-waveform".into())
             .relative()
-            .w_full()
             .h(sizes.waveform)
             .border_1()
             .border_color(transparent_black())
@@ -226,7 +225,6 @@ impl RenderOnce for AudioSpectrum {
         let (color, round) = (theme.colors.fg_muted, theme.radius(Radius::Sm));
         div()
             .debug_selector(|| "audio-spectrum".into())
-            .w_full()
             .h(theme.media().waveform)
             .flex()
             .items_end()

src/media/controls.rs

@@ -92,7 +92,6 @@ impl RenderOnce for VolumeControl {
             None => slider,
         };
         div()
-            .w_full()
             .flex()
             .items_center()
             .gap_2()

src/media/cropper.rs

@@ -200,7 +200,6 @@ impl RenderOnce for ImageCropper {
         div()
             .id(self.id.clone())
             .relative()
-            .w_full()
             .p(side / 2.0)
             .border_1()
             .border_color(transparent_black())

src/media/listen.rs

@@ -251,7 +251,6 @@ impl RenderOnce for AudioPlayer {
         };
         let left = format!("-{}", clock(self.length - self.at));
         div()
-            .w_full()
             .flex()
             .flex_col()
             .gap_3()

src/media/record.rs

@@ -255,7 +255,6 @@ impl RenderOnce for MicLevelMeter {
         let (unlit, round) = (colors.border, theme.radius(Radius::Sm));
         div()
             .debug_selector(|| "mic-level".into())
-            .w_full()
             .h(theme.meter_track())
             .flex()
             .gap_0p5()

src/media/scrubber.rs

@@ -264,7 +264,6 @@ impl RenderOnce for Scrubber {
         div()
             .id(self.id.clone())
             .debug_selector(|| "scrubber".into())
-            .w_full()
             .px(thumb / 2.0)
             .rounded(theme.radius(Radius::Sm))
             .border_1()

src/media/strip.rs

@@ -251,7 +251,6 @@ impl RenderOnce for VideoThumbnailStrip {
         let (pressed_strip, moved_strip) = (strip.clone(), strip.clone());
         div()
             .id(self.id.clone())
-            .w_full()
             .px(handle / 2.0)
             .border_1()
             .border_color(transparent_black())

src/media/subtitles.rs

@@ -309,7 +309,6 @@ impl RenderOnce for SubtitleEditor {
                 })
         });
         div()
-            .w_full()
             .flex()
             .flex_col()
             .gap_1()

src/media/thumbnail.rs

@@ -81,7 +81,6 @@ impl RenderOnce for ImageThumbnail {
             .children(label);
         div()
             .id(self.id)
-            .w_full()
             .rounded(outer)
             .border_1()
             .border_color(if self.selected {

src/media/upload.rs

@@ -189,7 +189,6 @@ impl RenderOnce for ImageUpload {
                 .into_any_element(),
         };
         div()
-            .w_full()
             .flex()
             .flex_col()
             .gap_3()