Desktop "Add node" button invokes PIN-pairing, not manual-node registration — no UI surface for nvpair-manual-nodes

Bắt đầu tại desktop/src/ui/components/AddNodeModal.tsx và đọc services/nvpair-manual-nodes/README.md để biết cấu trúc của yêu cầu node/add. Theo dõi relay hiện có và desktop/src/electron/service-bridge/manual-nodes-store.ts, bao gồm cả modular-supervisor.ts:replayManualNodes(). Công việc được hoàn tất khi luồng Add node cung cấp việc đăng ký các node thủ công, lưu mục nhập và phát lại mục nhập đó sau khi khởi động lại.

Desktop "Add node" button triggers PIN-pairing, not manual-node registration

Summary

The desktop UI's Settings → Cluster → Add node button (AddNodeModal.tsx)
is the only obvious entry point for adding a node by IP address, but it
actually invokes PIN-pairing (useInvitePairing().start(ip)), not the
nvpair-manual-nodes registration that a user would expect from the label
"Add node". There is no UI surface anywhere in the desktop app to add a
node to nvpair-manual-nodes. Combined with the in-memory-only state of
nvpair-manual-nodes, this means a user with a peer reachable over Tailscale
/ VPN has no documented path to make the peer stay online.

Reproduction

1. Open Settings → Cluster.
2. Click Add node.
3. Type the peer's Tailscale IP (e.g. 100.121.35.74) → click Invite.
4. Observe: pairing handshake fires (PIN prompt on the other side); on accept
   the cluster membership grows but configs/manual-nodes.json remains [].

Code reference

desktop/src/ui/components/AddNodeModal.tsx:

const handleManualInvite = useCallback(() => {
    const ip = manualIp.trim()
    if (!ip) return
    void pairing.start(ip)            // <- PIN-pairing, not nvpair-manual-nodes
}, [manualIp, pairing])

The render shows this only as a manual-IP invite — there is no second button or
tab for "register as manual node".

Why this matters

The nvpair-manual-nodes worker exists specifically to probe peers by IP when
mDNS can't reach them (e.g. across VPNs). It is documented in
services/nvpair-manual-nodes/README.md and supported via JSON-RPC
(node/add with { address, name?, tls_port?, mtls? }). The Electron-side
store (desktop/src/electron/service-bridge/manual-nodes-store.ts) already
persists entries in configs/manual-nodes.json and replays them via
modular-supervisor.ts:replayManualNodes() on startup. All the wiring exists
except the UI surface.

Suggested fix

Add a second control to AddNodeModal.tsx (e.g. a tab "Add as manual node"
or a checkbox "Skip pairing — register for direct probing only") that calls
the broker's node/add relay with { address, name }. The store already
saves on success.

Workaround

Edit ~/.config/Nvidia Corporation/Personal AI Router/configs/manual-nodes.json
by hand with the documented schema [{id, address, name}] and restart the app
— the supervisor will replay it on startup. See companion issue for the
upstream symptom this addresses.

Environment

• nvpair 0.1.1
• Linux 7.2.5-3-omarchy