feat: incorporate secrets into CI/CD pipeline and runtime configuration

[memreo]

Summary

Injects MongoDB and Google Gemini API secrets into the CI/CD pipeline and local runtime configuration:

1. Adds .env to .dockerignore in the Python service to prevent local secrets from being baked into the image.
2. Updates infra/docker-compose.yml to consume secrets from the host environment at runtime.
3. Injects workflow-level environment variables in .github/workflows/ci.yml from GitHub repository secrets (MONGODB_URI and GOOGLE_API_KEY).

Component

• Client: client/
• API contract: api/
• Spring ingestion: services/spring-ingestion/
• Spring logbook: services/spring-logbook/
• Spring alerts: services/spring-alerts/
• GenAI: services/py-intelligence/
• Infrastructure: infra/
• CI/CD: .github/workflows/
• Documentation

API Impact

• This does not change the API.

Testing

• I tested this locally.
• I added or updated tests.
• Tests are not applicable for this change.

Checklist

• Branch name follows (feat|fix)/(issue_id)/(name_of_issue).
• The change is limited to the intended component(s).
• Documentation was updated if needed.

Related Issue

Closes #62

[tahahundekari]

LGTM! Sorry again for the delay on the secrets for the server-side. Thank you!