chore: tighten public API and disable source maps

- exports: block ./types and ./utils subpaths from the "./*" wildcard so
  internal helpers compiled into dist/js/ are not importable by consumers
- tsconfig.build.json: disable sourceMap and declarationMap. Defaults embed
  original .ts content into .map files, which would ship the source inside
  the tarball despite files:["dist"] and inflate size without meaningful
  debuggability gains for a UI library

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: sangun-kang

package.json

@@ -45,6 +45,8 @@
       "import": "./dist/js/*/index.js",
       "default": "./dist/js/*/index.js"
     },
+    "./types": null,
+    "./utils": null,
     "./css/*.css": "./dist/css/*.css"
   },
   "files": [

tsconfig.build.json

@@ -4,8 +4,8 @@
     "noEmit": false,
     "outDir": "./dist/js",
     "declaration": true,
-    "declarationMap": true,
-    "sourceMap": true
+    "declarationMap": false,
+    "sourceMap": false
   },
   "include": ["src"],
   "exclude": [