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

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

Start in desktop/src/ui/components/AddNodeModal.tsx and read services/nvpair-manual-nodes/README.md for the node/add request shape. Trace the existing relay and desktop/src/electron/service-bridge/manual-nodes-store.ts, including modular-supervisor.ts:replayManualNodes(). Done means the Add node flow offers manual-node registration, saves the entry, and replays it after restart.