Replace the manual copy/paste workflow with a live fetch

[JSONbored]

Problem: The extension's only workflow today is manual copy/paste of discovery output — there's no live connection to the miner CLI or miner-ui at all.

Area: AMS / Extension

Proposal: Add a live fetch path to the local miner-ui API (once the localhost-reachability gap below is resolved), replacing manual paste as the primary flow while keeping paste as a fallback.

Deliverables:

• A working live-fetch mode in the extension.

Boundaries:

• Depends on resolving the localhost-reachability gap below.

[linear-code]

JSO-3519