fix(deps): declare playwright-core as direct dependency

playwright-cli.js requires `playwright-core/lib/tools/cli-client/program`
but only `playwright` is declared as a dependency. Under package
managers that isolate transitives (pnpm with the default `isolated`
linker), the require fails immediately on every install. Pinning
`playwright-core` to the same version as `playwright` removes the
dependency on hoisting and matches the existing transitive resolution.

Fixes #396

Author: av1155

package-lock.json

@@ -22,7 +22,8 @@
     "@types/node": "^25.2.1"
   },
   "dependencies": {
-    "playwright": "1.60.0-alpha-1777669338000"
+    "playwright": "1.60.0-alpha-1777669338000",
+    "playwright-core": "1.60.0-alpha-1777669338000"
   },
   "bin": {
     "playwright-cli": "playwright-cli.js"