feat(eth): use F3 for "finalized" and "safe" resolution in v1 APIs

[rvagg]

As per chat with @BigLep, this is how we backport F3 finalisation rules to v1 Eth APIs if we want to go with that path. It also comes with a future clean-up task that we should open an issue for if we merge this.

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Same rules as v2:

• "finalized" and "safe" resolve to whatever F3 has finalized
• Fall-back for "safe" is to 200 epochs behind head when F3 isn't operating
• Fall-back for "finalized" is 900 epochs behind head when F3 isn't operating

Run with LOTUS_ETH_V1_DISABLE_F3_FINALITY_RESOLUTION=1 to revert to the old resolution rules.

Future clean-up required:

• Remove LOTUS_ETH_V1_DISABLE_F3_FINALITY_RESOLUTION option
• Remove builder_chain.go split paths for v1 and v2 Eth module building - reuse same modules across v1 and v2.
• Simplify eth_api_f3_test.go to remove special rules for v1 vs v2 - test same rules

[Copilot]

Pull Request Overview

This PR updates the v1 Ethereum APIs to use F3 (Fast Finality) for "finalized" and "safe" block resolution, bringing v1 APIs in line with v2 APIs. The change includes a temporary environment variable to disable F3 finality resolution if needed.

• Updated v1 TipSetResolver to use F3 certificate provider with fallback behavior
• Added temporary environment variable LOTUS_ETH_V1_DISABLE_F3_FINALITY_RESOLUTION to revert to old resolution rules
• Updated test cases to reflect unified v1/v2 behavior expectations

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
node/modules/eth.go	Modified v1 TipSetResolver to use F3 certificate provider with environment variable override
itests/eth_api_f3_test.go	Updated test expectations to reflect unified v1/v2 F3 finality behavior

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[BigLep]

I like it, especially given we have the escape hatch. I'll create an issue for the followup work if @Kubuxu is on board with this change.

[Kubuxu]

Seems like a good way to approach it

[BigLep]

Cleanup work being tracked in #13315