chore(deps-dev): TypeScript 6 + fixes (#28)

Bump typescript devDependency 5.9.3 -> 6.0.3.

TS 6.0 no longer auto-includes the @types/node ambient globals for this
project's NodeNext config, so `node:fs`/`process`/`Buffer` etc. failed
with TS2591. Add `"types": ["node"]` to tsconfig compilerOptions (the
fix the TS6 error message itself recommends). tsconfig.test.json extends
this config and inherits the setting, so both the build and the test
compile pass.

Supersedes dependabot PR #16.

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

Author: mastermanas805

package-lock.json

@@ -56,7 +56,7 @@
   },
   "devDependencies": {
     "@types/node": "^25.9.1",
-    "typescript": "^5.9.3"
+    "typescript": "^6.0.3"
   },
   "engines": {
     "node": ">=18"

package.json

@@ -3,6 +3,7 @@
     "target": "ES2022",
     "module": "NodeNext",
     "moduleResolution": "NodeNext",
+    "types": ["node"],
     "outDir": "dist",
     "rootDir": "src",
     "strict": true,