fix(app): replace node-forge with native crypto for private key validation

[kyungseopk1m]

Fixes #3075

Problem

initializeApp() with a cert() credential calls require('node-forge') synchronously during ServiceAccount construction. Loading node-forge initializes a PRNG that uses Math.random(), which causes errors in environments that restrict non-deterministic APIs during static rendering — specifically Next.js App Router with Partial Pre-Rendering (PPR) / SSG:

Error: Route used Math.random() before accessing either uncached data or Request data...

Solution

Replace forge.pki.privateKeyFromPem() with Node.js built-in crypto.createPrivateKey(). This provides equivalent PEM validation while removing the node-forge dependency entirely.

Testing

All 6231 existing unit tests pass. The existing test should throw given an object with a malformed "private_key" property in credential-internal.spec.ts already covers the error path for invalid private keys.

Notes

• No public API changes
• Removes ~500KB dependency (node-forge)
• Related: fix: Replace node-forge with native crypto for private key validation #3051 proposed the same fix but was blocked by a CLA issue

[gemini-code-assist]

Code Review

This pull request updates the package version to 13.8.0 and removes the node-forge dependency. The logic for validating service account private keys in src/app/credential-internal.ts has been refactored to use the native Node.js crypto.createPrivateKey method instead of node-forge. I have no feedback to provide as there were no review comments.