feat: node workflow redesign — wizard auto-config, reset, MusicBrainz contact

Wizard (Electron):
- Auto-provisions node config (hub URL + username) from logged-in user
- node:start handles both cold start and restart of misconfigured daemon
- Waits for daemon to reach 'running', auto-links node key on hub
- probeNode accepts intermediate states for wizard progress feedback

Reset (meshbay-node reset):
- Unlinks node key from hub (DELETE /me/node_key, best-effort)
- Stops and disables daemon (systemctl --user disable --now)
- Erases ~/.config/meshbay, ~/.local/share/meshbay, ~/.local/state/meshbay

MusicBrainz contact:
- Resolved from owner's hub email instead of per-node roster config
- Removed musicbrainz_contact UI and WebRTC handshake field
- Removed set_musicbrainz_contact/musicbrainz_contact from roster

Node pairing:
- Added operator pairing banner on NodePage
- Added operator_paired flag to list_groups

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/api/users.py b/packages/meshbay-hub/src/meshbay_hub/api/users.py
index b1489ec..7db3fc9 100644
--- a/packages/meshbay-hub/src/meshbay_hub/api/users.py
+++ b/packages/meshbay-hub/src/meshbay_hub/api/users.py
@@ -625,6 +625,17 @@ async def register_node_key(
     return {"status": "stored", "pk_node_ed25519": body.pk_node_ed25519}
 
 
+@router.delete("/me/node_key")
+async def unlink_node_key(
+    current_user: User = Depends(get_current_user),
+    db: AsyncSession = Depends(get_db),
+):
+    """Remove the linked node key from the operator's account."""
+    current_user.pk_node_ed25519 = None
+    await db.commit()
+    return {"status": "unlinked"}
+
+
 # Key rotation used to live here (`PUT /me/keys`). Identity keys are per node
 # now, so rotating means `meshbay-node member unpin <user>` and pairing again with
 # a fresh code — an operator decision on the machine that pinned it, not a hub