fix devnet edge case

[raduchis]

epoch start trigger and force epoch start with minimum blocks per epoch

Reasoning behind the pull request

A 1-block epoch causes processIfFirstBlockAfterEpochStart to dirty the peer trie in memory, then createEpochStartBody fails to recreate it from DB because the root hash was never committed

Proposed changes

• Added minimumBlocksPerEpoch = 2 guard in trigger.Update() — epoch start is deferred until nonce >= epochStartNonce + 2, ensuring at least 2 blocks per epoch

Testing procedure

• ALLIN with rounds per epoch 0 or 1 maybe

Pre-requisites

Based on the Contributing Guidelines the PR author and the reviewers must check the following requirements are met:

• was the PR targeted to the correct branch?
• if this is a larger feature that probably needs more than one PR, is there a feat branch created?
• if this is a feat branch merging, do all satellite projects have a proper tag inside go.mod?

[Copilot]

Pull request overview

Adjusts the metachain epoch-start trigger to avoid a devnet edge case where an epoch could effectively last only one block, leading to inconsistent in-memory vs DB state during epoch-start processing.

Changes:

• Added a minimumBlocksPerEpoch = 2 guard to trigger.Update() so epoch start is deferred until at least 2 blocks exist in the current epoch.
• Added unit tests covering both normal epoch-start triggering and forced epoch-start behavior under the new minimum-blocks constraint.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
epochStart/metachain/trigger.go	Enforces a minimum number of blocks per epoch before allowing an epoch transition.
epochStart/metachain/trigger_test.go	Adds regression tests ensuring epoch start/forced epoch start won’t happen with only 1 block in the current epoch.

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[Copilot]

hasMinBlocksInEpoch := nonce >= epochStartNonce+minimumBlocksPerEpoch can overflow when epochStartNonce is close to math.MaxUint64, potentially making the comparison unexpectedly true/false and triggering epoch start incorrectly. Please rewrite the check to avoid uint64 addition overflow (e.g., compare using nonce >= epochStartNonce and then nonce-epochStartNonce >= minimumBlocksPerEpoch, or guard the addition with an overflow-safe check).

Suggested change

	hasMinBlocksInEpoch := nonce >= epochStartNonce+minimumBlocksPerEpoch
	hasMinBlocksInEpoch := nonce >= epochStartNonce && nonce-epochStartNonce >= minimumBlocksPerEpoch