perf(evm): discover non-Anvil fork endpoints once

[mattsse]

Fork resolution snapshots the endpoint identity (eth_chainId plus the anvil_nodeInfo probe) before and after every remote read, so an Anvil reset or profile change cannot slip in between. An endpoint without Anvil node info has nothing to revalidate, since its identity is derived from the chain ID alone, yet each step repeated the snapshot: cast run discovered the endpoint in run and again in TracingExecutor::get_fork, took three snapshots around the block and gas price reads in env_resolved, and two more around the block read in create_fork. That is 9 eth_chainId and 9 anvil_nodeInfo requests, sent sequentially before the replay starts. cast call --trace and forge test --fork-url go through the same sequence.

Such endpoints are now probed once: discovery returns the first snapshot without a confirming one when it finds no Anvil node info, and later snapshots reuse the cached discovery. Any probe failure still means "no Anvil" until node info is returned, endpoints identified as Anvil keep their strict revalidation around every read, and discover_fork_endpoint still always inspects the endpoint. The remote trace paths (--debug-trace-transaction, --debug-trace-call) use the same reuse for their before/after identity check. The one behavior difference is an Anvil endpoint whose first discovery probe fails: it is now treated as non-Anvil for the rest of the invocation instead of being picked up by the confirming snapshot. Resolution without a cached discovery still reads both snapshots and identifies it.

Results

Cold cast run 0x29582b47311ef26dc1d0677448ff520d646ac1d0489ca310d70294343991130b --rpc-url https://ethereum.reth.rs/rpc (fork cache for the block removed before every run), release builds:

	master	this PR
eth_chainId requests	9	1
anvil_nodeInfo requests	9	1
total RPC requests	57	41
wall time, median of 20 interleaved runs	1.69 s	1.29 s

Probe requests (eth_chainId + anvil_nodeInfo) on the other paths against the same endpoint:

	master	this PR
cast run --quick	9 + 9	1 + 1
cast call --trace	9 + 9	1 + 1
cast run --debug-trace-transaction	6 + 6	1 + 1
cast call --debug-trace-call	6 + 6	1 + 1
forge test --fork-url	9 + 9	1 + 1