Add hands-on tutorial: CIP-30 wallet connect and first preview transaction (Mesh)

## Problem
The Tutorials section currently has essentially one real hands-on guide (`local-cardano-payment-detector`). Newcomers who want a browser + wallet dApp path still hit a thin tutorials area (#115). The old Tools stub page was removed (#191), so we also need a clear “start building a dApp” entry that points at widely used tooling such as Mesh.

## Proposed solution
Add a second tutorial that walks through:

1. Connect a CIP-30 browser wallet
2. Build a simple payment transaction with Mesh (or equivalent maintained TS SDK)
3. Sign and submit on **preview** testnet
4. Confirm on an explorer
5. Short troubleshooting (network mismatch, missing collateral, API keys)

Include links to Mesh docs, faucet, and DevEx Getting Started.

## Acceptance criteria
- [ ] New tutorial page under `website/docs/tutorials/`
- [ ] Listed in Tutorials navigation / Getting Started
- [ ] Uses preview testnet (no mainnet funds required)
- [ ] Clear prerequisites and copy-pasteable steps
- [ ] `npm run build` succeeds

## Related
- #115
- #191 (tools stub removed; this helps replace that entry path)

Commencez par comparer le tutoriel local-cardano-payment-detector existant avec le contenu de website/docs/tutorials/. Ajoutez le nouveau tutoriel et mettez à jour la navigation Tutorials ou Getting Started avec des liens vers Mesh docs, le faucet et DevEx Getting Started. La tâche est considérée comme terminée lorsque le guide couvre la connexion CIP-30, une transaction de prévisualisation Mesh, la signature, la soumission, la confirmation dans l’explorateur et le dépannage, et que npm run build réussit.

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