Graceful degradation before partnership/SSH is set up

Fix 1 — Monitor partner card (common.php + monitor.php):
  vv_remote_hosts_stats() no longer skips hosts with no API key.
  Returns no_api_key:true entry instead. Monitor JS renders
  "API key not configured — complete Onboard to enable" instead
  of a blank space.

Fix 2 — rawconf push not alarming pre-onboard (config.php + scheduler.php):
  Probe failures (Tailscale not found, plugin not installed) now carry
  ready:false. JS treats ready:false results silently — button shows
  "✓ Saved" not "push failed: HOST2" before SSH is set up.
  Only genuine post-onboard failures (ready not false) show as errors.

Fix 3 — Partnership Onboard button (partnership.php):
  Disabled with tooltip when no partner hostname is in master.conf.
  When partner configured but not onboarded, adds explanation note:
  "Onboard will generate your SSH key, exchange it with the partner..."
  No partner configured: "Edit master.conf and set HOST2."

Plugin/unraid/pages/partnership.php

@@ -207,11 +207,15 @@ function _renderActions(nodes, cfg) {
   const remoteOpts = remotes.map(n =>
     `<option value="${n.slot}">${n.id} — ${n.hostname}</option>`).join('');
 
+  const hasPartner = remotes.length > 0 && remotes.some(n => n.hostname);
+
   let html = '<div class="vv-pt-actions">';
 
-  // Onboard
+  // Onboard — disabled until a partner hostname is configured in master.conf
   html += `<button class="vv-pt-action-btn run" onclick="vvPtOnboard(this)"
-    title="Run partnership_onboard.sh — auto-detects role (run on mirror first, then owner)">
+    ${!hasPartner ? 'disabled title="Add partner hostname to master.conf first (Scheduler → master.conf)"' :
+                    'title="Run partnership_onboard.sh — auto-detects role (run on mirror first, then owner)"'}
+    ${!hasPartner ? 'style="opacity:.35;cursor:default;"' : ''}>
     ▶ Onboard
   </button>`;
 
@@ -223,6 +227,18 @@ function _renderActions(nodes, cfg) {
 
   html += '</div>';
 
+  // Contextual note under actions
+  if (!hasPartner) {
+    html += `<div style="font-size:11px;color:#444;margin-top:8px;">
+      No partner hostname configured. Edit master.conf (Scheduler tab) and set HOST2.
+    </div>`;
+  } else if (!cfg.enabled) {
+    html += `<div style="font-size:11px;color:#555;margin-top:8px;">
+      Onboard will generate your SSH key, exchange it with the partner, and establish the partnership.
+      Run on the mirror (HOST2) first, then on the owner (HOST1).
+    </div>`;
+  }
+
   // Transfer — show manual command, too destructive to one-click
   if (cfg.enabled && isOwner) {
     const confirmStr = 'i-understand-this-transfers-ownership';