Fix model-linker drag handle alignment and sizing

- Add align-self: flex-start for proper positioning
- Change dimensions to 30x30px square
- Adjust border-radius to 8px
- Add margin-top and box-sizing for consistent layout

web/css/linker-shell.css

@@ -85,16 +85,20 @@
 
 #model-linker-drag-handle {
     display: flex;
+    align-self: flex-start;
     align-items: center;
     justify-content: center;
-    height: 24px;
-    padding: 0 7px;
+    width: 30px;
+    height: 30px;
+    margin-top: 1px;
+    padding: 0;
     opacity: 0.82;
     cursor: grab;
     user-select: none;
     border: 1px solid rgba(255, 255, 255, 0.11);
-    border-radius: 6px;
+    border-radius: 8px;
     background: rgba(255, 255, 255, 0.025);
+    box-sizing: border-box;
 }
 
 #model-linker-modal .ml-window-btn {