feat(frontend): implement pow worker and service layer

[DecentAgeCoder]

Motivation

This change introduces the foundational components required to support a Proof-of-Work (PoW)–protected allowSigning operation. Specifically, it prepares a scheduler that will execute the requestSignerCycles function within a Web Worker context.

Note: The PoW worker is defined but not yet initialized via initPowProtectorWorker(..). This will be completed in a subsequent pull request.

Changes

• Implemented a Scheduler-compliant scheduler using the existing SchedulerTimer to support timed execution of PoW jobs.
• Introduced a PoW service layer responsible for initializing the PowProtectorWorker via the initPowProtectorWorker function.
• Added the core PoW Protection Web Worker (PowProtectorWorker).
• Defined PowProtectorWorkerInitResult to describe the worker's initialization return structure, and introduced the new PowProtectorWorker type.
• Added a message handler onPowProtectionMessage for processing postMessage communications from the Web Worker on the application side.
• Registered onPowProtectionMessage(msg) to the the global onmessage handler within the web application to handle messages dispatched by the PoW worker.

[AntonioVentilii]

maybe make it functional? maybe with self-called functions?

const nonce = ...

[DecentAgeCoder]

I can do that but It could reduce readability. Since this is a critical code a more 'procedural' presentation could therefore be desired here. I will give it a try.

[AntonioVentilii]

thank you! in any case, if you prefer this implementation, maybe preferable to use while (prefix > target) and refactor the logic?

[DecentAgeCoder]

A do-while-loop and a conditional-loop will be less readable since they duplicate the condition.

[AntonioVentilii]

Yes, my idea was something like

const target = BigInt(Math.floor(0xffffffff / difficulty));

const solvePowChallengeRecursive = async (
  timestamp: bigint,
  nonce: bigint = 0n
): Promise<bigint> => {
  const challengeStr = `${timestamp}.${nonce}`;
  const hashHex = await hashText(challengeStr);
  const prefix = BigInt(parseInt(hashHex.slice(0, 8), 16));

  return prefix <= target
    ? nonce
    : solveChallengeRecursive(timestamp, nonce + 1n);
}

const nonce = await solvePowChallengeRecursive(...)

But anyway, let's proceed with the while loop for readability. May you please change it to have a condition instead of while(true)

[AntonioVentilii]

Ah! and for safety, let's put an hard coded limit of N iterations that raise an error

P.S. and tests

[DecentAgeCoder]

Added feedback on comments

[DecentAgeCoder]

I can do that but It could reduce readability. Since this is a critical code a more 'procedural' presentation could therefore be desired here. I will give it a try.

[AntonioVentilii]

Ah! and for safety, let's put an hard coded limit of N iterations that raise an error

P.S. and tests