quickshell: load wallpaper state synchronously

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

settings/quickshell.nix

@@ -611,6 +611,15 @@ in
                         property string name: "${defaultWall}"
                     }
                     onLoadFailed: if (path !== "") writeAdapter()
+                    // blockLoading alone does NOT make this synchronous:
+                    // preload already started an async read when path was
+                    // set, and a JsonAdapter only waits for dataChanged — it
+                    // never calls text(), the one read blockLoading gates.
+                    // Without this, shell.qml's startup applyTheme() saw the
+                    // default wallpaper, then the real one a moment later,
+                    // and two concurrent theme-apply runs raced for the
+                    // Hyprland borders. text() here joins the in-flight read.
+                    Component.onCompleted: text()
                 }
 
                 // Unknown name (wallpaper deleted from the repo since it was