Add environment variable validation on startup

[Aharshi3614]

Description

Server fails with cryptic errors if required environment variables are missing. Users don't know which variable is missing.

Goals

• Validate all required env variables at startup
• Display clear error message for missing variables
• Exit gracefully if validation fails

Implementation

• Define required env vars list
• Check each variable exists
• Log error and exit if any missing

[github-actions]

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[github-actions]

The proposal suggests implementing environment variable validation during server startup to address issues with unclear error messages when variables are missing. The plan includes defining a list of required variables, checking for their existence, logging clear error messages for any missing variables, and ensuring the server exits gracefully if validation fails.