Extend query scheduler protocol to handle multiple request types, including health checks

[coderabbitai]

Context

The query scheduler currently expects all connections to follow a specific protocol. Health checks and other diagnostic operations would benefit from a more flexible protocol that supports multiple request types.

Proposal

Extend the protocol to include a header byte indicating request type. This would allow the scheduler to:

• Recognise health check requests
• Log health status appropriately
• Respond with predefined responses or close the connection as appropriate
• Support future request types without breaking existing functionality

Benefits

• Cleaner separation of concerns between health checks and normal operations
• Better logging and observability
• More robust health checking mechanism
• Foundation for future protocol extensions

References

• Related PR: feat(deployment)!: Migrate package orchestration to Docker Compose (resolves #1177). #1178
• Discussion: feat(deployment)!: Migrate package orchestration to Docker Compose (resolves #1177). #1178 (comment)
• Requested by: @junhaoliao