Fix: OAuth key generation - add kid, alg, use fields and update to ES256K
Fixed setup-did-and-keys.sh to generate proper OAuth-compatible JWK with:
- kid (Key ID) - required for OAuth client
- alg: "ES256K" - secp256k1 signing algorithm
- use: "sig" - key usage indicator
Updated oauth-service.ts to use ES256K algorithm to match the secp256k1
keys generated by both setup-did-and-keys.sh and oauth-keyset-json.sh.
This fixes the error: "Client authentication method 'private_key_jwt'
requires at least one 'ES256' signing key with a 'kid' property"
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>