build: expand typecheck coverage beyond src

tsconfig.typecheck.json

@@ -0,0 +1,12 @@
+{
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "rootDir": ".",
+    "noEmit": true,
+    "declaration": false,
+    "declarationMap": false,
+    "sourceMap": false
+  },
+  "include": ["src/**/*", "launcher/**/*.ts", "scripts/*.ts"],
+  "exclude": ["node_modules", "dist", "vendor"]
+}