Add drivechain peg activity explorer

[ekulkisnek]

Summary

• add an Elements-specific peg activity view for deposits, withdrawals, bundle commitments, and acknowledgements
• expose the view through navigation and document the corresponding API contract
• lock the production frontend dependencies and add CI coverage for reproducible builds

Why

LayerTwoLabs Liquid Signet exposes BIP300 peg lifecycle data that was not visible in the standard Esplora interface. This gives operators a read-only explorer view of that lifecycle while retaining the existing Esplora transaction and asset views.

Validation

• production frontend build completed successfully
• live UI served on localhost and returned the expected explorer application
• Esplora API and Elements RPC agreed at height 2673 and on the exact tip hash
• responsive peg activity UI was verified against the indexed Liquid Signet fixture

[ekulkisnek]

Closing this upstream PR. The Liquid drivechain adaptation will be maintained as a separate repository instead.