feat: Grafana default dashboard construction and docs

[justinthelaw]

User Story

As a cluster administrator
I want Grafana dashboards to visualize and alert me to LeapfrogAI issues
So that maintenance and continuous improvement of production clusters is easier

As a delivery engineer
I want docs to create my own Grafana dashboards
So that I can create custom views

Use the identified metrics in #1017

Acceptance Criteria

All components listed in EPIC: Observability and Metrics

Describe alternatives you've considered

N/A

Additional context

Examples:

• Grafana* dashboards to visualize the following backend and Kubernetes metrics in real-time:
  • Tokens per second
  • Latency and error rates
  • Resource utilization (CPU, memory)
  • Active requests
  • Pod and node health