Audit: Verify assignedTxs is populated for all transaction types

[tcsenpai]

Context

The assignedTxs field on GCRMain accounts was defined but never populated. A fix was added to HandleGCR.apply() to track transactions for the sender account.

What was done

• Modified HandleGCR.apply() to add tx.hash to sender.assignedTxs after successful GCR edit operations
• Added addAssignedTx() helper method to handle the update with duplicate prevention

What needs to be audited

1. Verify all transaction types populate assignedTxs:
   • balance ✓ (goes through HandleGCR.apply)
   • nonce ✓ (goes through HandleGCR.apply)
   • identity ✓ (goes through HandleGCR.apply)
   • storageProgram ✓ (goes through HandleGCR.apply)
   • tlsnotary ✓ (goes through HandleGCR.apply)
   • assign - TODO implementation
   • subnetsTx - TODO implementation
   • smartContract - TODO implementation
   • escrow - TODO implementation
2. Check if recipients should also have assignedTxs updated:
   • For transfers, should the receiver also have the tx in their assignedTxs?
   • For storage programs, should the storage address have a reference?
3. Verify historical transactions:
   • Existing accounts may have empty assignedTxs
   • Consider migration script to backfill from chain data

Technical Details

• File: src/libs/blockchain/gcr/handleGCR.ts
• Method: HandleGCR.apply() and HandleGCR.addAssignedTx()
• Entity: GCRMain.assignedTxs: string[]