Fix BigInteger.modInverse DoS in shipped bundles

[Kr0emer]

Summary

Fix a denial-of-service issue in the shipped jsrsasign bundles where BigInteger.modInverse(0, odd_modulus) could enter an infinite loop.

What changed

• Synced bundled bnModInverse implementations with the normalized safe logic already present in source
• Updated the generated browser and npm bundles affected by the source/bundle desync
• Added a regression test covering modInverse(0, 9) through the npm entrypoint

Validation

• Reproduced the hang locally against npm/lib/jsrsasign.js with a timeout-based PoC before the fix
• Verified the fixed bundle now returns 0 instead of hanging
• Added and executed a regression test locally with a lightweight harness