Fan out manual miner discovery to Fleet Nodes

[ankitgoswami]

🤖 This issue was created by my AI agent.

Problem

In Fleet → Miners → Add miners, Scan network fans out to confirmed, connected Fleet Nodes. Manual IP-list, IP-range, and subnet discovery does not; it runs from the Fleet server.

This prevents manual discovery at remote sites when the Fleet server cannot route to the miners but an on-site Fleet Node can.

Example:

• Fleet Node: 172.16.25.19
• Remote miner subnet: 172.16.21.0/24
• The Fleet Node can route to the miner subnet, but the Fleet server may not.

Expected behavior

Operators can route manual IP-list, IP-range, and subnet discovery through an eligible Fleet Node. The UI should make the execution location clear when more than one node is available.

Acceptance criteria

• Manual IP-list, IP-range, and subnet discovery can execute on a confirmed, connected Fleet Node.
• The requested targets and discovery ports reach the selected node unchanged, subject to existing validation and scan limits.
• Results stream back through the existing discovery flow and are deduplicated consistently.
• The UI reports when no eligible Fleet Node is connected.
• Existing Fleet-server discovery remains available where appropriate.