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/messaging/call.rs

@@ -206,7 +206,6 @@ impl RenderOnce for VoiceCallBar {
             .then(|| AvatarGroup::new(self.people).max(3).size(AvatarSize::Xs));
         div()
             .debug_selector(|| "voice-call-bar".into())
-            .w_full()
             .flex()
             .flex_wrap()
             .items_center()

src/messaging/channels.rs

@@ -272,14 +272,11 @@ impl RenderOnce for ChannelList {
                 sections.section(title, rows)
             },
         );
-        div()
-            .debug_selector(|| "channel-list".into())
-            .w_full()
-            .child(
-                sections
-                    .selected(self.open)
-                    .on_select(open.clone())
-                    .on_activate(open),
-            )
+        div().debug_selector(|| "channel-list".into()).child(
+            sections
+                .selected(self.open)
+                .on_select(open.clone())
+                .on_activate(open),
+        )
     }
 }

src/messaging/gifs.rs

@@ -295,7 +295,6 @@ impl RenderOnce for GifPicker {
             .then(|| Masonry::new((self.id.clone(), "gifs"), 2, gap).children(tiles));
         div()
             .debug_selector(|| "gif-picker".into())
-            .w_full()
             .flex()
             .flex_col()
             .gap_2()

src/messaging/header.rs

@@ -104,7 +104,6 @@ impl RenderOnce for ChannelHeader {
         };
         div()
             .debug_selector(|| "channel-header".into())
-            .w_full()
             .flex()
             .flex_wrap()
             .items_center()

src/messaging/members.rs

@@ -193,7 +193,6 @@ impl RenderOnce for MemberList {
         });
         div()
             .debug_selector(|| "member-list".into())
-            .w_full()
             .children(empty)
             .when(!self.members.is_empty(), |list| {
                 list.child(

src/messaging/messages.rs

@@ -141,7 +141,6 @@ impl RenderOnce for ChatMessage {
             .id(self.id.clone())
             .debug_selector(move || format!("message {}", self.id))
             .group(group)
-            .w_full()
             .flex()
             .gap_3()
             .px_3()
@@ -192,7 +191,6 @@ impl RenderOnce for UnreadDivider {
         let theme = cx.theme();
         let danger = theme.colors.danger;
         div()
-            .w_full()
             .flex()
             .items_center()
             .gap_2()

src/messaging/people.rs

@@ -176,7 +176,6 @@ impl RenderOnce for UserProfileCard {
         });
         div()
             .debug_selector(|| "profile-card".into())
-            .w_full()
             .flex()
             .flex_col()
             .gap_3()

src/messaging/pins.rs

@@ -152,7 +152,6 @@ impl RenderOnce for PinnedMessages {
         });
         div()
             .debug_selector(|| "pinned-messages".into())
-            .w_full()
             .flex()
             .flex_col()
             .gap_1()

src/messaging/status.rs

@@ -300,7 +300,6 @@ impl RenderOnce for StatusSetter {
         });
         div()
             .debug_selector(|| "status-setter".into())
-            .w_full()
             .flex()
             .flex_col()
             .gap_4()

src/messaging/thread.rs

@@ -68,7 +68,6 @@ impl RenderOnce for MessageThread {
         div()
             .id(self.id)
             .debug_selector(|| "message-thread".into())
-            .w_full()
             .flex()
             .items_center()
             .gap_2()

src/messaging/tiles.rs

@@ -191,7 +191,6 @@ impl RenderOnce for VideoCallGrid {
         div()
             .debug_selector(|| "video-call-grid".into())
             .relative()
-            .w_full()
             .flex()
             .flex_col()
             .children(rows)
@@ -321,7 +320,6 @@ impl RenderOnce for ScreenShareView {
         });
         div()
             .debug_selector(|| "screen-share".into())
-            .w_full()
             .flex()
             .flex_col()
             .gap_2()