chore(deps): support TypeScript 6 (widen peer to ^5 || ^6)

- Add typescript ^6.0.0 as devDependency for verified builds
- Widen peerDependency to ^5 || ^6 to keep TS 5 consumers supported
- tsconfig.build.json: set explicit rootDir (required by TS 6 when outDir is set)
- tsconfig.build.json: replace deprecated moduleResolution "node" with "bundler"

package.json

@@ -58,10 +58,11 @@
   },
   "devDependencies": {
     "@types/bun": "^1.3.14",
-    "@types/node": "^25.0.0"
+    "@types/node": "^25.0.0",
+    "typescript": "^6.0.0"
   },
   "peerDependencies": {
-    "typescript": "^5"
+    "typescript": "^5 || ^6"
   },
   "engines": {
     "node": ">=18.0.0"