UX: Surface health information on upstream pages

Problem

For Virtual Registry GA, Platform engineers need a quick and reliable way to understand if their upstreams are in a healthy (i.e., connected/reachable) state. While a future Virtual Registry dashboard (#544030) will provide an aggregated view across all package types, we shall deliver this visibility sooner by surfacing health information within the Virtual Registries pages we have released.

Adding this information at the package type level will enable engineers to quickly spot and act on potential issues, improving operational awareness and reducing the time needed to identify upstream problems, without waiting for the full dashboard implementation.

Solution

Surface upstream health on the Upstreams list, Upstream detail page and Registry detail page.

Out of scope for this issue, but considered for future iterations, is expanding the definition of "health" to include operational signals such as response time, cache hit ratio, and total uptime.

Design Requirements

• Make upstream health status immediately understandable at a glance
• Use clear visual indicators (e.g., icons, colours, text) to convey connectivity status
• Ensure placement supports quick discovery without disrupting existing workflows
• Consider both high-level overview and paths to more detailed information

This issue is related to UX: Surface health information on registry pages (#569343). It is recommended to complete this upstream health implementation first, since registry health is derived from it.