Merge pull request #1347 from Stremio/docs/contributing-guide

Docs: Add contribution guide

CONTRIBUTING.md

@@ -0,0 +1,60 @@
+# Contributing to Stremio Web
+
+Thank you for helping improve Stremio Web.
+
+## Before you start
+
+- Search existing issues and pull requests before starting work.
+- Discuss large features or architectural changes with the maintainers first.
+- Base your branch on `development` and keep each pull request focused on one change.
+
+## Development
+
+Stremio Web requires Node.js 22 or newer and pnpm 11 or newer.
+
+```sh
+pnpm install
+pnpm start
+```
+
+When changing code:
+
+- Fix the root cause with the smallest practical change.
+- Do not include unrelated refactors, formatting, or cleanup.
+- Match the patterns and style of the surrounding code.
+- Use pnpm and do not add npm or yarn lockfiles.
+- Keep CommonJS in existing JavaScript files and prefer TypeScript for new files.
+- Reuse existing components, hooks, helpers, aliases, and local LESS modules.
+- Avoid new effects or dependencies when existing code can solve the problem directly.
+- Do not add new Jest or other test files unless a maintainer requests them.
+
+## Translations
+
+Do not add hardcoded user-facing text. Add translation keys to the public
+[`stremio-translations`](https://github.com/Stremio/stremio-translations) repository and update the dependency when needed.
+
+Run the translation scan after changing translation keys:
+
+```sh
+pnpm run scan-translations
+```
+
+## Validation
+
+Run the checks relevant to your change before opening a pull request:
+
+```sh
+pnpm run lint
+pnpm test
+pnpm run build
+git diff --check
+```
+
+## Pull requests
+
+- Use a clear branch name without tool or agent prefixes.
+- Keep commit subjects, the pull request title, and its description concise.
+- Use subject-only commit messages and keep unrelated changes in separate commits or pull requests.
+- Explain what changed, why it changed, and how it was verified.
+- Include screenshots or a short recording for visible UI changes.
+- Write pull request descriptions and review replies yourself; do not paste generated responses into the review discussion.