v3.1.0: Update web flasher version badge and firmware binary

Bumps the web flasher version display to v3.1.0 and refreshes
firmware.bin to match the v3.1.0 build output.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

index.html

@@ -94,7 +94,7 @@
 <div class="container">
     <h1>EISWOLFS FLIGHTRADAR CYD</h1>
     <div class="subtitle">Firmware Flash Utility</div>
-    <div class="version-badge">Version: v3.0.1</div>
+    <div class="version-badge">Version: v3.1.0</div>
 
     <p>Install the latest Flightradar firmware directly from your browser to your Cheap Yellow Display.</p>