Update backend run instructions in docs

[areibman]

📥 Pull Request

📘 Description Added comprehensive documentation for setting up and running the backend services located in the app/ directory. This includes:

• A new docs/backend-setup.md guide covering architecture, prerequisites, configuration, database setup, observability, development commands, and troubleshooting.
• An update to docs/README.md to improve the overall documentation structure and link directly to the new backend setup guide.

🧪 Testing The instructions were compiled based on an analysis of the project's app/ directory, docker-compose.yaml, and relevant configuration files. Manual verification of the setup steps is recommended.

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[cursor[bot]]

Cursor Agent can help with this pull request. Just @cursor in comments and I'll start working on changes in this branch. _{Learn more about Cursor Agents}

[github-actions[bot]]

This pull request has been automatically marked as stale because it has not had any activity in the last 14 days.

If no updates are made within 7 days, this PR will be automatically closed.