Redo integration-testing

cc @WiktorStarczewski
The web-sdk integration tests seem to rely on rust-sdk's test-node script and a manually pinned rust-sdk commit. This is a bit hacky. cc
This also means:

* web-sdk's fee path is not actually tested (it does not use the genesis etc)
* changes to rust-sdk's test setup can break web-sdk CI
* the pin needs to be updated manually when versions change
* running the same setup locally is awkward

We already hit this when rust-sdk enabled fees by default and the web-sdk tests started failing. The workaround was to disable fees again. We should at least:

1. Fund test accounts from the genesis funders and run CI with fees enabled.
2. Move the test-node startup logic into web-sdk.
3. Keep the genesis config in web-sdk instead of depending on rust-sdk's unpublished test crate.
4. Add a simple local command to start the same test node used in CI.

Look at the existing integration tests in the web-sdk to see how they currently invoke the rust-sdk's test-node script. Examine the CI configuration to understand the current setup. The goal is to move the test-node startup logic and genesis configuration into the web-sdk repository, decoupling it from the rust-sdk. A good starting point is to replicate the test node startup in a local script within web-sdk, ensuring test accounts are funded from genesis for fee-enabled tests.

Rédigé par le modèle d'indexation à partir du texte de l'issue.