As a platform admin, I want the registry server to observe MCP servers across configured namespaces, so that servers deployed by the operator in other namespaces are discoverable

[rdimitrov]

The ToolHive Operator supports configurable namespace scoping but the registry server is hardcoded to only observe its own namespace. This means MCP servers deployed by the operator in other namespaces are invisible to the registry.

What needs to happen

• Align the registry server's namespace observation and RBAC permissions with the operator's scoping model so both components can work across the same set of namespaces.

This includes:

• Adding namespace configuration to the registry server (config + Helm chart RBAC)
• Ensuring compatibility with the operator's existing namespace scoping
• Updating documentation to match the actual implementation