Add a dedicated diagnostics dashboard command for summarizing system health and configuration

[pugsley76]

Description:
A dashboard command should summarize Glassbox system health, configuration, cache state, and plugin status in one place.

Work to be done:
Implement a diagnostics command that reports health and environment status.

Implementation procedure:

1. Add a diagnostics command to the CLI.
2. Collect health data from RPC endpoints, cache status, configuration, plugin load state, and simulator compatibility.
3. Present the information in a readable dashboard format with severity indicators.
4. Add tests for diagnostics output.
5. Document the diagnostic dashboard.

Acceptance criteria:

• There is a diagnostics command summarizing key system health and configuration.
• The output is readable and highlights issues.
• Tests verify diagnostics data collection.
• Documentation explains the command.

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