feat(tracing): add BlockTracer for block-level transaction tracing

[mattsse]

Adds BlockTracer, BlockTracerIter, BlockTracingError, and BlockExecutorFactoryExt to support tracing transactions within block execution context.

Key features

• BlockTracer: Wraps BlockExecutor and provides tracing methods:
  • trace / trace_many / try_trace_many - similar to TxTracer
  • trace_transaction - traces a single transaction by hash, replaying prior txs with inspector disabled
• BlockTracerIter: Automatically calls apply_pre_execution_changes on first iteration with inspector disabled
• BlockTracingError: Separates PreExecution, Evm, and Hook errors for proper error handling
• BlockExecutorFactoryExt: Extension trait providing create_block_tracer convenience method

Usage

Trace all transactions

let mut tracer = factory.create_block_tracer(&mut state, env, ctx, inspector);
for result in tracer.trace_many(txs, |ctx| { /* ... */ }) {
    match result {
        Ok(output) => { /* handle trace output */ }
        Err(BlockTracingError::PreExecution(e)) => { /* system call failed */ }
        Err(BlockTracingError::Evm(e)) => { /* tx execution failed */ }
        Err(BlockTracingError::Hook(e)) => { /* hook returned error */ }
    }
}
let (evm, block_result) = tracer.finish()?;

Trace a single transaction

let tracer = factory.create_block_tracer(&mut state, env, ctx, inspector);
// Replays prior txs with inspector disabled, then traces target tx (not committed)
if let Some(output) = tracer.trace_transaction(txs, target_hash)? {
    // handle output.result and output.inspector
}