chore: update .env.sample with actual variables

[hteppl]

No description provided.

[greptile-apps]

Greptile Summary

Updates the operator-facing environment sample to document three existing runtime configuration variables.

• Adds the SNI verification setting.
• Adds nftables logging and reply-traffic settings.
• Uses values consistent with the existing runtime defaults and accepted boolean format.

Confidence Score: 5/5

The PR appears safe to merge because the documented variables and values align with the existing runtime configuration contract.

No actionable failures remain; all three additions use recognized lowercase boolean values and preserve existing effective defaults.

Important Files Changed

Filename	Overview
.env.sample	Documents existing SNI and nftables environment variables using valid names, formats, and default values.

_{Reviews (1): Last reviewed commit: "chore: update .env.sample with actual va..." | Re-trigger Greptile}