30. Add a web .env.example and startup config validation guide

[Cedarich]

Area: Web
Complexity: Easy

Summary:
Help contributors start the web app correctly by documenting required env vars and validating them early.

Acceptance Criteria:

• A .env.example exists for the active web app.
• Required variables are documented with safe placeholders.
• Missing or invalid config is surfaced clearly during startup.

[Purity-Euphemia]

Good Day Maintainer, I have experience and would review the issue, implement a clean solution, test it, and submit a pull request.

[Purity-Euphemia]

Good Day Maintainer, I have experience and would review the issue, implement a clean solution, test it, and submit a pull request.

[Purity-Euphemia]

Good Day Maintainer, I have experience and would review the issue, implement a clean solution, test it, and submit a pull request.

[Purity-Euphemia]

Good Day Maintainer, I have experience and would review the issue, implement a clean solution, test it, and submit a pull request.

[Purity-Euphemia]

Good Day Maintainer, I have experience and would review the issue, implement a clean solution, test it, and submit a pull request.

[benzy018]

Good day, Maintainer. I have relevant experience and would like to work on this issue. I will review the existing configuration, improve the startup configuration guide, and submit a well-tested pull request.

[Ayinkx01]

Hi l would like to take this job

[blvckmamba81-sketch]

Hello Maintainer, I’m interested in working on this issue. I’ll review the requirements, implement a clean solution, test it thoroughly, and submit a high-quality pull request. Looking forward to contributing.