feat: Allow fetching rollkitmngr state in rollkit-migrate command for attester sets

[Copilot]

The rollkit-migrate command previously assumed single validator setups and used the first validator as the sequencer. This failed for chains using attester sets where the first validator may not be the actual sequencer.

Problem

When using an attester set (multiple validators), the migration command would fail with:

expected exactly one validator in the last validators, found N

This occurred because the command couldn't determine which validator was the actual sequencer from the CometBFT validator set alone.

Solution

Enhanced the migration command to fetch sequencer information from the rollkitmngr module state when multiple validators are present:

• Smart Sequencer Detection: Attempts to query rollkitmngr state to identify the correct sequencer
• Robust Database Access: Tries multiple key formats to maximize compatibility with various Cosmos SDK storage patterns
• Backward Compatibility: Falls back to original single-validator logic when rollkitmngr state is unavailable
• Validation: Ensures the sequencer from rollkitmngr state exists in the validator set
• Clear Error Messages: Provides detailed error information for troubleshooting

Key Changes

1. Enhanced createRollkitMigrationGenesis(): Added conditional logic to query rollkitmngr state for multiple validators
2. New getSequencerFromRollkitMngrState(): Handles database access and sequencer extraction with multiple key format strategies
3. Comprehensive Testing: Added test coverage for all scenarios including edge cases and error conditions

Example Usage

# Now works for chains with attester sets
rollkit-migrate

# Fallback behavior for single validator chains (unchanged)
rollkit-migrate

The implementation maintains full backward compatibility while enabling migration for chains using attester sets.

Fixes #164.

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[julienrbrt]

this is far too hacky. recreate the collections and use the store.
then use that collections to query the state.
the collections definition is defined in the keeper.go

[Copilot]

Replaced the hacky multiple key format attempts with proper collections framework usage. The implementation now recreates the collections schema as defined in keeper.go and uses sequencerCollection.Get(ctx) to query the state properly. Commit c0a9468

[julienrbrt]

consider the store is read only. DO NOT CHANGE THE APP STORE. you should solely get info from it.

[Copilot]

Fixed. Removed the store modification and now only read from the database directly using the collections key format. The store remains read-only throughout the process. Commit 4aa5521

[julienrbrt]

can we error joins those errors? as it will be lost otherwise.

[Copilot]

Fixed. Now using errors.Join to properly combine the validator count error with the rollkitmngr state error, preserving the error chain for better debugging. Commit 229d533