fix: update renamed Lucide icons (Wand2 -> Wand, Columns -> Columns2) (#149)

Lucide v0.577 dropped Wand2 and Columns from the icons object used
for dynamic lookup. Named exports still exist as aliases, but the
landing site and tools index use icons[name] which fails silently.

Updates shared constants and web app icon-map to use the current names.

packages/shared/src/constants.ts

@@ -158,7 +158,7 @@ export const TOOLS: Tool[] = [
     name: "Object Eraser",
     description: "Remove unwanted objects with AI",
     category: "ai",
-    icon: "Wand2",
+    icon: "Wand",
     route: "/erase-object",
   },
   {
@@ -377,7 +377,7 @@ export const TOOLS: Tool[] = [
     name: "Stitch / Combine",
     description: "Join images side by side, stacked, or in a grid",
     category: "layout",
-    icon: "Columns",
+    icon: "Columns2",
     route: "/stitch",
   },
   {