[feature] update proof-of-work to allow setting required rounds (#4186)

# Description

This updates our proof-of-work middleware, NoLLaMas, to work on a more easily configurable algorithm (thank you f0x for bringing this to my attention!). Instead of requiring that a solution with pre-determined number of '0' chars be found, it now pre-computes a result with a pre-determined nonce value that it expects the client to iterate up-to. (though with some level of jitter applied, to prevent it being too-easily gamed). This allows the user to configure roughly how many hash-encode rounds they want their clients to have to complete.

## Checklist

- [x] I/we have read the [GoToSocial contribution guidelines](https://codeberg.org/superseriousbusiness/gotosocial/src/branch/main/CONTRIBUTING.md).
- [x] I/we have discussed the proposed changes already, either in an issue on the repository, or in the Matrix chat.
- [x] I/we have not leveraged AI to create the proposed changes.
- [x] I/we have performed a self-review of added code.
- [x] I/we have written code that is legible and maintainable by others.
- [x] I/we have commented the added code, particularly in hard-to-understand areas.
- [x] I/we have made any necessary changes to documentation.
- [ ] I/we have added tests that cover new code.
- [x] I/we have run tests and they pass locally with the changes.
- [x] I/we have run `go fmt ./...` and `golangci-lint run`.

Reviewed-on: https://codeberg.org/superseriousbusiness/gotosocial/pulls/4186
Co-authored-by: kim <grufwub@gmail.com>
Co-committed-by: kim <grufwub@gmail.com>

web/source/nollamas/index.js

@@ -43,18 +43,18 @@ document.addEventListener("DOMContentLoaded", function() {
 
 	// Read the challenge and difficulty from
 	// data attributes on the nollamas section.
+	const seed = nollamas.dataset.nollamasSeed;
 	const challenge = nollamas.dataset.nollamasChallenge;
-	const difficulty = nollamas.dataset.nollamasDifficulty;
 
-	console.log("challenge:", challenge);     // eslint-disable-line no-console
-	console.log("difficulty:", difficulty); // eslint-disable-line no-console
+	console.log("seed:", seed);           // eslint-disable-line no-console
+	console.log("challenge:", challenge); // eslint-disable-line no-console
 
 	// Prepare the worker with task function.
 	const worker = new Worker("/assets/dist/nollamasworker.js");
 	const startTime = performance.now();
 	worker.postMessage({
 		challenge: challenge,
-		difficulty: difficulty,
+		seed:      seed,
 	});
 
 	// Set the main worker function.