Add an .nvmrc

[RaymondAbiola]

Summary

The repository does not pin a Node version for version managers, so contributors run whatever their shell provides. An .nvmrc makes the intended runtime a one-command switch.

Acceptance criteria

• .nvmrc pins the Node version the project targets.
• The pinned version matches the documented minimum.
• The README mentions it.

Getting started

Fork this repository, clone your fork, and add this repo as upstream:

git clone https://github.com/<your-username>/tricklepay-frontend.git
cd tricklepay-frontend
git remote add upstream https://github.com/TricklePay/tricklepay-frontend.git

Create a branch for this issue:

git checkout -b chore/issue-168

Suggested commit message:

chore: add an nvmrc

Run npm run lint, npm run typecheck, npm test, and npm run build before opening a pull request and linking this issue.