feat(web): add shadcn/ui base components (Button, Input, ScrollArea)

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

web/components.json

@@ -0,0 +1,16 @@
+{
+  "$schema": "https://ui.shadcn.com/schema.json",
+  "style": "default",
+  "rsc": false,
+  "tsx": true,
+  "tailwind": {
+    "config": "client/tailwind.config.ts",
+    "css": "client/src/index.css",
+    "baseColor": "zinc",
+    "cssVariables": true
+  },
+  "aliases": {
+    "components": "@/components",
+    "utils": "@/lib/utils"
+  }
+}