Add bunext playground for local component development

Runs at http://localhost:7010 via bun run dev. The playground imports the library from src through a committed symlink and tsconfig path alias, so component edits hot-reload without a build step. It has its own install root and is excluded from the published package.

dev/tsconfig.json

@@ -0,0 +1,23 @@
+{
+    "compilerOptions": {
+        "lib": ["ESNext", "DOM", "DOM.Iterable"],
+        "target": "ESNext",
+        "module": "ESNext",
+        "moduleDetection": "force",
+        "jsx": "react-jsx",
+        "moduleResolution": "bundler",
+        "strict": true,
+        "skipLibCheck": true,
+        "esModuleInterop": true,
+        "noFallthroughCasesInSwitch": true,
+        "resolveJsonModule": true,
+        "forceConsistentCasingInFileNames": true,
+        "noEmit": true,
+        "baseUrl": ".",
+        "paths": {
+            "@moduletrace/twui": ["./twui/index.ts"],
+            "@moduletrace/twui/*": ["./twui/*"]
+        }
+    },
+    "include": ["src", "bunext.config.ts"]
+}