Add FAQ and Common Errors sections to developer setup documentation

[coderNini]

Summary

Developers encounter setup errors that are not addressed anywhere in the current documentation, leading to hours of unguided troubleshooting. Adding an FAQ and/or Common Errors section would significantly improve the onboarding experience.

Proposed Changes

• Add a general FAQ section addressing common questions across the setup process
• Add a Common Errors subsection (at minimum within the Rails Database section) covering known issues with versioning, file paths, and command failures
• Document the specific errors and solutions encountered so far — a contributor has offered to provide detailed error logs and solutions upon request

Make changes in #408 (and refer to comments for further detail)

[beanscg]

Bean Labs took a public-source pass on this issue.

The narrowest useful next step looks like: Offer a developer-setup FAQ/Common Errors comment focused on Rails database setup, versioning, file paths, and command failures named in the issue.

Public evidence checked:

• Live public issue read: open, no assignees, zero comments; body asks for FAQ/Common Errors in setup docs and calls out Rails Database, versioning, file paths, and command failures.
• Public web search for repo pull requests tied to issue 429 returned no visible open PR coverage.

A good acceptance check would be a docs diff that changes only the affected wording/link and renders without stale references.

No PR opened from this pass.