fix: pin route ordering and star icon overlap in grid view

Move GET /pinned and PATCH /pinned/reorder before GET /{tree_id} to
prevent FastAPI from matching "pinned" as a UUID path parameter (422).
Relocate star button from absolute positioning into the header row to
avoid overlapping privacy icons and category badges.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/components/library/TreeGridView.tsx

@@ -37,26 +37,6 @@ export function TreeGridView({
           key={tree.id}
           className="relative bg-card border border-border rounded-2xl p-4 transition-all hover:-translate-y-0.5 hover:border-primary/30 hover:shadow-md sm:p-6"
         >
-          {onTogglePin && (
-            <button
-              onClick={(e) => {
-                e.stopPropagation()
-                e.preventDefault()
-                onTogglePin(tree.id)
-              }}
-              disabled={pinLoadingTreeIds?.has(tree.id)}
-              aria-label={pinnedTreeIds?.has(tree.id) ? 'Remove from favorites' : 'Add to favorites'}
-              className={cn(
-                'absolute top-3 right-3 z-10 rounded-md p-1 transition-colors',
-                pinnedTreeIds?.has(tree.id)
-                  ? 'text-amber-400 hover:text-amber-300'
-                  : 'text-muted-foreground/40 hover:text-amber-400',
-                pinLoadingTreeIds?.has(tree.id) && 'opacity-50 pointer-events-none'
-              )}
-            >
-              <Star size={16} fill={pinnedTreeIds?.has(tree.id) ? 'currentColor' : 'none'} />
-            </button>
-          )}
           <div className="mb-2 flex items-start justify-between gap-2">
             <div className="flex items-center gap-2">
               <h3 className="font-semibold text-foreground">{tree.name}</h3>
@@ -74,6 +54,26 @@ export function TreeGridView({
               )}
             </div>
             <div className="flex items-center gap-2">
+              {onTogglePin && (
+                <button
+                  onClick={(e) => {
+                    e.stopPropagation()
+                    e.preventDefault()
+                    onTogglePin(tree.id)
+                  }}
+                  disabled={pinLoadingTreeIds?.has(tree.id)}
+                  aria-label={pinnedTreeIds?.has(tree.id) ? 'Remove from favorites' : 'Add to favorites'}
+                  className={cn(
+                    'rounded-md p-1 transition-colors',
+                    pinnedTreeIds?.has(tree.id)
+                      ? 'text-amber-400 hover:text-amber-300'
+                      : 'text-muted-foreground/40 hover:text-amber-400',
+                    pinLoadingTreeIds?.has(tree.id) && 'opacity-50 pointer-events-none'
+                  )}
+                >
+                  <Star size={14} fill={pinnedTreeIds?.has(tree.id) ? 'currentColor' : 'none'} />
+                </button>
+              )}
               {tree.is_public ? (
                 <span title="Public tree">
                   <Globe className="h-4 w-4 text-muted-foreground" />