Display Linux introspection vendor extension data

[bburda]

Summary

Display Linux introspection data from vendor extension endpoints in the entity detail view.

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Proposed solution (optional)

• Show process-level diagnostics (CPU, memory, container info) in entity detail
• Fetch from GET /{entity_type}/{entity_id}/x-medkit-procfs, /x-medkit-systemd, /x-medkit-container
• Gracefully handle 404 when plugins are not loaded
• Display as collapsible section in entity detail view

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Additional context (optional)

Depends on sovd_web_ui#42 (client migration). These are plugin-registered vendor extension routes - may not appear in OpenAPI spec if plugins register routes dynamically.