feat: add Stellar transaction simulator (dry-run) before submit

[Ryjen1]

Wire simulateTransaction against Soroban RPC into StellarSend so users see predicted fees, return values, and contract events before signing. Simulation failures disable the Send button with decoded contract errors; network errors fall back to letting the user try anyway.

Closes #24

[vercel]

Someone is attempting to deploy a commit to the truthixify's projects Team on Vercel.

A member of the Team first needs to authorize it.

[drips-wave]

@Ryjen1 Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

Learn more about application limits

[truthixify]

Heads up — we've just set up a develop branch as the integration target for all Drips × Stellar Wave contributions, and I've retargeted this PR's base from main to develop on your behalf. The diff is unchanged; nothing to do on your end.

Going forward, please branch from and target develop. We'll periodically merge develop → main as we cut releases. Thanks for contributing!

[truthixify]

The simulator wiring is what we want for issue #24: simulateTransaction against Soroban RPC, SimulationCard UI, useSimulateTransaction hook, error decoding helpers, plus Playwright coverage.

StellarSend.tsx is rewritten heavily in this PR and #13 (input validation) just merged into develop with overlapping changes. Could you rebase?

git fetch origin
git rebase origin/develop
git push --force-with-lease

When you resolve StellarSend.tsx, keep both: the validation constants and balance-debounce from develop, layered with your debounced simulate-call flow. The SimulationCard component, hook, and lib files should land cleanly. Thanks @Ryjen1.