View the current number of nodes in a dev neighborhood via a UI

Description: This is the first story to incorporate infrastructure observability via an end-to-end implementation of our block explorer, Talib. We should be able to present the current total number of nodes and the number of active nodes via the UI.

Story ROI:
This story enables users and node operators to check on infrastructure performance and health via metrics.

As a user, I want to view the current total number of nodes and active nodes in a neighborhood so that I stay informed.

• Should be achievable via a UI.
• Should be available from the network API.
• Should be able to target a specific neighborhood.
• Should present the current total number of nodes and active nodes.
• Should present an error message to the user (in UI) if there is an error retrieving the data.
• Should present a warning to the user (in UI) if there are upstream errors.
• Should be able to be demoed as an E2E implementation.

The issue names no files, tests, or implementation entry points. Start by locating the Talib UI and network API, then trace how a neighborhood is selected and how node metrics are exposed. Done means the UI shows total and active nodes for a selected neighborhood, handles retrieval and upstream errors, and supports an end-to-end demo.