implement JWT circuit & ZK Spartan2 Intergration.

[0xVikasRushi]

Description

This PR implements major optimizations to the JWT circuit, reducing constraints and simplifying the circuit architecture. The changes include removing redundant parameters, implementing bulk extraction for EC public keys, and enabling Circom compiler optimizations.

Metric	Before Optimization	After Optimization	Reduction %
Constraints	2,457,687	1,701,803	≈30.76%

Closes #22 (partial - addresses JWT circuit optimization and Circom compilation optimization)

What's Changed

Optimizations

• Set Circom optimization flag to -O2 for improved circuit compilation and reduced constraint count
• Removed unnecessary header extraction logic and eliminated maxB64HeaderLength parameter
• Simplified circuit to only extract from JWT payload
• Added ECPublicKeyExtractor_Optimized template using VarShiftLeft for bulk extraction instead of per-character selection
• Made EC coordinate patterns ("x":", "y":") explicit match patterns
• Added messages output for decoded claims for commitment sharing
• Added Circom version and removed unnecessary output files
• Include zk Spartan2 Integration