fix: resolve meteor WebSocket race condition and setup apt-get failure

Meteor: onopen callback used closure variable _ws instead of `this`,
so a double-click during CONNECTING state sent on the wrong socket.
Also clean up any in-progress connection on re-start, not just running ones.

Setup: make apt-get update non-fatal so third-party repo errors
(e.g. stale PPAs on Debian) don't abort the entire install.

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

setup.sh

@@ -1370,7 +1370,10 @@ install_debian_packages() {
   CURRENT_STEP=0
 
   progress "Updating APT package lists"
-  $SUDO apt-get update -y >/dev/null
+  if ! $SUDO apt-get update -y >/dev/null 2>&1; then
+    warn "apt-get update reported errors (possibly from third-party repos on your system)."
+    warn "Continuing anyway — if package installs fail, check your APT sources."
+  fi
 
   progress "Installing RTL-SDR"
   if ! $IS_DRAGONOS; then

static/js/modes/meteor.js

@@ -88,7 +88,7 @@ const MeteorScatter = (function () {
     }
 
     function start() {
-        if (_running) stop();
+        if (_running || _ws) stop();
 
         const freq = parseFloat(document.getElementById('meteorFrequency')?.value) || 143.05;
         const gain = parseFloat(document.getElementById('meteorGain')?.value) || 0;
@@ -126,9 +126,13 @@ const MeteorScatter = (function () {
         }
 
         _ws.onopen = function () {
+            // Guard against race: if start() was called again before this
+            // connection opened, _ws now points to a different socket.
+            if (_ws !== this) { try { this.close(); } catch (e) { /* */ } return; }
+
             _running = true;
             _updateUI();
-            _ws.send(JSON.stringify({
+            this.send(JSON.stringify({
                 cmd: 'start',
                 frequency_mhz: freq,
                 gain: gain === 0 ? 'auto' : gain,