feat(slint): search input slides into the JUMP TO bar inline

Moves the in-page search out of the body column into the JUMP TO
bar itself, with a width animation so the input slides over the
tabs from the right edge on open (and back to 0 on close), matching
Tauri's `.page-search.open` behaviour.

JumpNavBar:
  - New `search-text` (in-out) and `search-text-edited` callback so
    the parent owns the query string + filter wiring while the bar
    owns the input UI.
  - Center region is a single Rectangle whose `clip: true` hides the
    expanding search-overlay until it has width. The overlay's
    width binds to `search-open ? parent.width : 0px` with a 200ms
    ease-in-out animation, so the tabs visually disappear behind it.
  - Tabs' TouchAreas are disabled while the search is open, so the
    visible click target is just the input.
  - Search icon flips to an X glyph and stays accent-tinted while
    open, signalling "click again to close".

ArtistPageView:
  - The standalone in-page search Rectangle in the body column is
    removed. The 24px head spacer stays so the loading state /
    Popular Tracks header sit at the same y as before.
  - JumpNavBar wired: search-text-edited routes through to
    ArtistActions.search; search-clicked toggles search-visible and
    also clears the query (and re-runs the empty search) on close
    so the filter releases as the input disappears.

cc

crates/qbz-slint/ui/artist/ArtistPageView.slint

@@ -501,66 +501,12 @@ export component ArtistPageView inherits Rectangle {
                     horizontal-stretch: 1;
                     spacing: 0px;
 
+            // 24px head spacing then straight into the loading state /
+            // Popular Tracks header — the in-page search now lives
+            // inside the JUMP TO bar (see jump-nav below), no longer
+            // a separate row in the body column.
             Rectangle { height: 24px; }
 
-            // --- In-page search ---------------------------------------------
-            // Single client-side substring filter — applied to Popular
-            // Tracks (title + artist) and to every release-section
-            // album title. Hidden by default; the JUMP TO bar's search
-            // icon toggles `search-visible` (mirrors Tauri's search
-            // toggle inside `.jump-nav`).
-            if root.search-visible
-                && (!ArtistState.loading || ArtistState.top-tracks.length > 0):
-            Rectangle {
-                height: 36px;
-                border-radius: Radius.sm;
-                background: Theme.surface-card;
-                border-width: 1px;
-                border-color: artist-search.has-focus
-                    ? Theme.border-subtle
-                    : transparent;
-                HorizontalLayout {
-                    padding-left: 12px;
-                    padding-right: 12px;
-                    spacing: 8px;
-                    VerticalLayout {
-                        alignment: center;
-                        horizontal-stretch: 0;
-                        QbzIcon {
-                            source: @image-url("../assets/icons/search.svg");
-                            width: 14px;
-                            height: 14px;
-                            tint: Theme.text-muted;
-                        }
-                    }
-                    Rectangle {
-                        horizontal-stretch: 1;
-                        artist-search := TextInput {
-                            width: 100%;
-                            height: 100%;
-                            color: Theme.text-primary;
-                            font-size: Typography.body;
-                            vertical-alignment: center;
-                            single-line: true;
-                            edited => {
-                                ArtistActions.search(self.text);
-                            }
-                        }
-                        Text {
-                            visible: artist-search.text == "";
-                            width: 100%;
-                            height: 100%;
-                            text: @tr("Search this page…");
-                            color: Theme.text-muted;
-                            font-size: Typography.body;
-                            vertical-alignment: center;
-                        }
-                    }
-                }
-            }
-
-            Rectangle { height: 12px; }
-
             if ArtistState.loading && ArtistState.top-tracks.length == 0: Rectangle {
                 height: 280px;
                 VerticalLayout {
@@ -757,6 +703,13 @@ export component ArtistPageView inherits Rectangle {
         }
         search-clicked => {
             root.search-visible = !root.search-visible;
+            if (!root.search-visible) {
+                self.search-text = "";
+                ArtistActions.search("");
+            }
+        }
+        search-text-edited(query) => {
+            ArtistActions.search(query);
         }
     }