chore: simplify environment configuration

[WA11AX]

Summary

• drop unused REDIS, SMTP and analytics variables
• streamline example env file to required settings
• update backend README with current env vars

Testing

• npm test
• npm run lint:check
• npm run type-check

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https://chatgpt.com/codex/tasks/task_e_689cdc1fc72483278736b800e681bbd9

[Copilot]

Pull Request Overview

This PR simplifies environment configuration by removing unused environment variables and streamlining the setup documentation. The changes focus on keeping only the essential configuration options while removing Redis, SMTP, and analytics variables that are not currently utilized.

Key Changes:

• Removed unused environment variable schema definitions (Redis, SMTP, analytics)
• Updated documentation to reflect current required environment variables
• Simplified the example environment file to essential settings only

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
server/config.ts	Removed schema definitions for unused Redis, SMTP, and analytics environment variables
server/README.md	Updated environment variables documentation with current required variables
.env.example	Streamlined to show only essential configuration options, removing numerous unused variables

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