feat: Add Immich favicon to heatmap app

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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

heatmap-app/Dockerfile

@@ -4,6 +4,7 @@ WORKDIR /app
 
 COPY server.js .
 COPY index.html .
+COPY favicon.png .
 
 EXPOSE 3000
 

heatmap-app/index.html

@@ -4,6 +4,7 @@
     <meta charset="UTF-8">
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <title>Immich Photo Heatmap</title>
+    <link rel="icon" type="image/png" href="/favicon.png">
     <link rel="stylesheet" href="https://unpkg.com/leaflet@1.9.4/dist/leaflet.css" />
     <style>
         * { margin: 0; padding: 0; box-sizing: border-box; }