fix(anvil): use fee manager as Tempo fork coinbase

[BROCCOLO1D]

Summary

• Defaults Anvil Tempo forks to the Tempo fee manager address as block.coinbase/beneficiary when no genesis coinbase is supplied.
• Applies the same default when anvil_reset starts forking from a non-forked Tempo node.
• Keeps explicit genesis coinbase configuration unchanged.

Why

Tempo mainnet maps the zero-address validator token to a DONOTUSE sentinel. In fork mode, Anvil previously inherited the default zero beneficiary, so state-changing transactions could hit Tempo fee collection failures and then appear as missing receipts indefinitely. Tempo node-side simulation already uses the fee-manager sentinel to fall back to PathUSD.

Changes

• Centralized the Tempo fork beneficiary default in NodeConfig.
• Applied the default during Tempo fork startup and during anvil_reset when it initializes a fork from a non-forked node.
• Added regression coverage for both startup forks and reset-to-fork flows.

Validation

• git diff --check
• cargo fmt --check
• cargo test -p anvil --test it tempo::test_tempo

Scope

Small Anvil Tempo fork/default-beneficiary behavior only; does not alter non-Tempo forks, standalone Tempo nodes, or explicit genesis coinbase settings.

Closes #14866

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two findings.

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two follow-up comments from local repros.

[BROCCOLO1D]

Addressed the Tempo fork beneficiary follow-ups: the fee-manager default now only applies while the beneficiary is still zero, so a runtime anvil_setCoinbase value survives anvil_reset into fork mode; after genesis handling, default Genesis::default() still gets the Tempo fee-manager beneficiary. Added targeted regressions for both cases and reran cargo fmt --check, git diff --check, and the three focused Tempo tests.

[BROCCOLO1D]

Addressed the load-state follow-up in cb92dff: Backend::load_state now normalizes zero beneficiaries for Tempo forks after restoring the saved block env, covering both startup --load-state and runtime anvil_loadState. Added focused regressions for both paths.

Validation:

• cargo fmt --check
• git diff --check
• cargo test -p anvil --test it loaded_zero_beneficiary_state -- --nocapture
• cargo test -p anvil --test it load_state_uses_fee_manager -- --nocapture
• cargo test -p anvil --test it tempo::test_tempo -- --nocapture

[mablr]

I just fixed a weak write lock pattern.

Sgtm, thanks.

[figtracer]

lgtm