Safeguard FeeHistory Estimator

[dimriou]

This PR:

• Checks for nil entries in feeHistory's rewards.
• Adds a minimum CacheTimeout check.
• Switches to non-blocking refresh to avoid getting stuck
• Now makes maxFeePerGas and priorityFeeThreshold updates consistent - prevents priorityFeeThreshold being lower than maxFeePerGas at a given instance, which can trigger false positive connectivity errors.
• Unifies dynamic fee variables under one dynamic fee cache structure.
• Fixes a bug where base wouldn't update if the maxFeePerGas and priorityFeeThreshold were not available.
• Introduces a newNoMempoolBaseFeeBufferPercentage for chains without a mempool i.e. Arbitrum, to prevent insufficient base fee errors.
• Improves structure and name conventions across the board

[github-actions]

⚠️ API Diff Results - github.com/smartcontractkit/chainlink-evm

⚠️ Breaking Changes (1)

pkg/gas.(*FeeHistoryEstimator) (1)

• RefreshDynamicPrice — 🗑️ Removed

✅ Compatible Changes (3)

pkg/gas (2)

• MinimumCacheTimeout — ➕ Added

• NoMempoolBaseFeeBufferPercentage — ➕ Added

pkg/gas.(*FeeHistoryEstimator) (1)

• RefreshDynamicFee — ➕ Added

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[Copilot]

Pull request overview

This PR hardens the FeeHistoryEstimator against edge cases from eth_feeHistory responses and reduces the risk of bump operations blocking on refresh signaling.

Changes:

• Add a minimum CacheTimeout validation during FeeHistoryEstimator.Start().
• Guard against nil percentile entries in feeHistory.Reward when computing priority fee stats.
• Make refresh signaling non-blocking by buffering refreshCh and using a best-effort send helper.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
pkg/gas/fee_history_estimator.go	Adds CacheTimeout validation, nil-reward handling, caps max dynamic fee fields, and switches refresh signaling to non-blocking behavior.
pkg/gas/fee_history_estimator_test.go	Updates tests to use t.Context() and adds a startup validation test for CacheTimeout.

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