Implied volatility solver and gas optimizations

DeFiMath now ships an on-chain implied-volatility solver:

• First implementation of impliedVolatility for vanilla options
• Iterative optimization pass — gas and accuracy improvements for both call and put paths
• Compiler-level tuning: viaIR and updated optimizer runs
• Updated math reference tables with the new results

The IV solver completes the core options-pricing toolkit needed for protocols that mark positions, settle, or rebalance against live vol.