Challenge: Build a Custom Instruction

Construct a custom Solana instruction that could be used to interact with a program. You'll define the program ID, the accounts involved, and the instruction data.

Requirements

• Create a function that accepts programId (PublicKey), payer (PublicKey), dataAccount (PublicKey), and amount (number)
• Return an instruction object with:
  • programId: the program to call
  • keys: an array of AccountMeta objects (payer as signer + writable, dataAccount as writable)
  • data: a Uint8Array containing the amount encoded as 8 bytes (little-endian u64)
• Use DataView to encode the amount as a little-endian 64-bit unsigned integer