feat: integrate shadcn/ui, add Button component, and refactor App UI

Cargo.lock

@@ -689,6 +689,7 @@ dependencies = [
  "serde",
  "serde_json",
  "shared",
+ "tailwind_fuse",
  "uuid",
  "wasm-bindgen",
  "web-sys",
@@ -2225,6 +2226,15 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "tailwind_fuse"
+version = "0.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7ca71fb01735fbc6fa13e9390d7a3037dde97053c0b65c0c72c0159cd009d26b"
+dependencies = [
+ "nom",
+]
+
 [[package]]
 name = "thiserror"
 version = "1.0.69"