Security Fix: Prevent Private Key Leak in solanaRPC.ts

[TobieTom]

Security Fix: Private Key Leak in Frontend Error Handling

Severity: Critical
Vulnerability Type: Information Exposure (CWE-532)

Description:
This Pull Request fixes a critical security vulnerability in frontend/src/solanaRPC.ts. previously, the sendToken method explicitly logged the user's raw, plaintext private key to the browser console (console.log) whenever a key length validation error occurred.

Changes:

• Removed the console.log statement in the error handling block of sendToken.
• Ensures sensitive key material is never written to stdout or application logs.

Testing:

• Verified locally with a Jest reproduction script (tests/poc_key_leak.ts).
• Confirmed that the private key is no longer printed to the console when the error condition is triggered.