Update .env.mainnet

[Madmaxs2]

Improved Environment Configuration Organization

Changes Made

• Grouped related environment variables into logical sections:
  • Engine configuration
  • Node basic settings
  • Metrics settings
  • Network settings
  • P2P Bootnodes
• Added descriptive section headers

Benefits

• Enhanced readability with clear separation of concerns
• Improved maintainability and easier troubleshooting
• Better developer experience with logical grouping

Technical Details

• No functional changes
• All values remain unchanged
• Only organization and documentation improved

This change makes it easier to work with the configuration file and reduces the likelihood of configuration-related issues.

[cb-heimdall]

🟡 Heimdall Review Status

Requirement	Status	More Info
Reviews	🟡 0/1	Denominator calculation Show calculation 1 if user is bot 0 1 if user is external 0 From .codeflow.yml 1 Additional review requirements Show calculation Max 0 0 From CODEOWNERS 0 Global minimum 0 Max 1 1 1 if commit is unverified 0 Sum 1