feat(explorer): take batch ttl from env

[Oppen]

Add a new BATCH_TTL_MINUTES environment variable for the explorer.
This variable stores the expected time in minutes we'll wait before
marking a Pending batch as Unverified in the UI.

Type of change

Please delete options that are not relevant.

• New feature
• Bug fix
• Optimization
• Refactor

Testing

1. Bring up a devnet
2. Bring up the explorer with different settings in your .env for BATCH_TTL_MINUTES
3. Check that the Age at which batches get marked match the values you use in the different screens

Relevant pages: home, batches, individual batch.

Checklist

• “Hotfix” to testnet, everything else to staging
• Linked to Github Issue
• This change depends on code or research by an external entity
  • Acknowledgements were updated to give credit
• Unit tests added
• This change requires new documentation.
  • Documentation has been added/updated.
• This change is an Optimization
  • Benchmarks added/run
• Has a known issue
  • Link to the open issue addressing it
• If your PR changes the Operator compatibility (Ex: Upgrade prover versions)
  • This PR adds compatibility for operator for both versions and do not change batcher/docs/examples
  • This PR updates batcher and docs/examples to the newer version. This requires the operator are already updated to be compatible