feat(revmc-reth): hot contract JIT compilation for reth/Tempo

[gakonst]

Summary

Adds revmc-reth crate for automatic JIT compilation of hot contracts in reth, OP-reth, and Tempo.

Features

• Hot contract detection: Tracks cumulative gas per bytecode hash, queues for compilation when threshold exceeded
• Background compilation: Worker threads compile contracts asynchronously (default: 2 threads)
• LRU cache: Configurable cache size (default: 1024 contracts)
• Thread-safe: Uses parking_lot and channels, no unsafe statics
• Zero-config fallback: Always falls back to interpreter for uncompiled bytecode

Configuration

// Presets
RevmcConfig::default()        // Standard config
RevmcConfig::low_memory()     // Smaller cache, single worker
RevmcConfig::high_performance() // Larger cache, more workers

// Custom
RevmcConfig::default()
    .with_enabled(true)           // CLI flag support
    .with_hot_threshold(500_000)  // Gas threshold
    .with_cache_size(2048)        // Max cached functions

Integration

Works with all three targets via revm's handler system:

• reth/OP-reth: Hook execute_frame handler
• Tempo: Each call in AA multi-call batch tracked independently

Closes

Replaces PR #73 (revmc-worker) with a cleaner, safer implementation.

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Stacked on main (post #80 merge).