Add runtime analytics env configuration

[KirillTonic]

Summary

• document the runtime Amplitude API key and analytics salt settings for Docker Compose installs
• keep analytics env values scoped to textual-api and textual-worker
• explicitly blank those env values on ML, Roberta, ASR, and log-shipper services when they inherit .env

Verification

• yq '.' docker-compose.yml >/dev/null
• yq '.' docker-compose-with-gpus.yml >/dev/null

Related Solar PR: https://github.com/TonicAI/solar/pull/3023