refactor: move OP EVM code into alloy-op-evm newtypes

[theochap]

Summary

• Introduce OpTx and OpTxError newtype wrappers in alloy-op-evm to hold all OP-specific EVM implementations previously in alloy-evm's op module
• Move spec ID mapping and EvmEnv constructors as free functions (evm_env_for_op_block, evm_env_for_op_next_block)
• Add TryIntoTxEnv<OpTx> for OpTransactionRequest behind rpc feature
• Add TransactionEnv impl for OpTx behind reth feature
• Update op-reth, kona, and custom-node example to use new types
• Remove alloy-evm op feature usage from kona crates

This is the companion PR to alloy-rs/evm#312 which removes the OP-specific code from alloy-evm. Together they decouple alloy-evm from Optimism, using newtype wrappers to satisfy Rust's orphan rule.

Test plan

• cargo clippy passes with no warnings
• cargo test -p alloy-op-evm — 24 tests pass
• Full workspace cargo check passes

🤖 Generated with Claude Code

[wiz-inc-a178a98b5d]

Wiz Scan Summary

Scanner	Findings
Vulnerabilities	2  1  2
Sensitive Data	-
Secrets	-
IaC Misconfigurations	-
SAST Findings	-
Software Management Findings	-
Total	2  1  2

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[codecov]

Codecov Report

❌ Patch coverage is 39.38679% with 257 lines in your changes missing coverage. Please review.
✅ Project coverage is 75.3%. Comparing base (8106d08) to head (b9c5431).
⚠️ Report is 15 commits behind head on develop.

Files with missing lines	Patch %	Lines
rust/kona/bin/client/src/fpvm_evm/tx.rs	0.0%	122 Missing ⚠️
rust/op-reth/crates/evm/src/tx.rs	32.6%	95 Missing ⚠️
rust/alloy-op-evm/src/env.rs	84.0%	18 Missing ⚠️
rust/alloy-op-evm/src/error.rs	22.2%	14 Missing ⚠️
rust/op-reth/crates/rpc/src/error.rs	0.0%	6 Missing ⚠️
rust/kona/bin/host/src/interop/handler.rs	0.0%	1 Missing ⚠️
rust/kona/crates/proof/executor/src/test_utils.rs	50.0%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop   #19536      +/-   ##
===========================================
  Coverage     75.3%    75.3%              
===========================================
  Files          194      485     +291     
  Lines        11276    60694   +49418     
===========================================
+ Hits          8493    45735   +37242     
- Misses        2639    14959   +12320     
+ Partials       144        0     -144     

Flag	Coverage Δ
cannon-go-tests-64	?
contracts-bedrock-tests	?
unit	75.3% <39.3%> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
rust/alloy-op-evm/src/block/mod.rs	96.4% <100.0%> (ø)
rust/alloy-op-evm/src/lib.rs	91.3% <100.0%> (ø)
rust/kona/bin/client/src/fpvm_evm/factory.rs	0.0% <ø> (ø)
rust/kona/crates/proof/executor/src/db/mod.rs	96.5% <ø> (ø)
rust/op-reth/crates/evm/src/lib.rs	99.7% <100.0%> (ø)
rust/kona/bin/host/src/interop/handler.rs	38.1% <0.0%> (ø)
rust/kona/crates/proof/executor/src/test_utils.rs	22.6% <50.0%> (ø)
rust/op-reth/crates/rpc/src/error.rs	0.0% <0.0%> (ø)
rust/alloy-op-evm/src/error.rs	22.2% <22.2%> (ø)
rust/alloy-op-evm/src/env.rs	84.0% <84.0%> (ø)
... and 2 more

... and 667 files with indirect coverage changes

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[theochap]

Last commit moves the newtype to kona and op-reth to remove the dependency of alloy-op-evm on reth. We need to make the OpEvmFactory generic over the transaction type