feat(ui): new equalizer logo, favicon link, fix favicon path

- icon.svg / icon-192/512.png: blue→purple equalizer gradient design
- nginx.conf: add /app/ alias so reverse-proxy prefix resolves assets
- vite.config.js: base /app/ + %BASE_URL% in favicon links so path
  resolves correctly whether app is served at / or /app/
- ic_launcher.xml: same equalizer design for Android app icon

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

android/app/src/main/res/drawable/ic_launcher.xml

@@ -1,13 +1,37 @@
 <?xml version="1.0" encoding="utf-8"?>
 <vector xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:aapt="http://schemas.android.com/aapt"
     android:width="108dp"
     android:height="108dp"
     android:viewportWidth="108"
     android:viewportHeight="108">
+
+    <!-- Background -->
     <path
-        android:fillColor="#1a1a2e"
-        android:pathData="M0,0h108v108h-108z" />
+        android:fillColor="#07070f"
+        android:pathData="M0,0H108V108H0Z"/>
+
+    <!-- Subtle blue glow -->
     <path
-        android:fillColor="#e040fb"
-        android:pathData="M54,27v23.24c-1.33-0.78-2.87-1.24-4.5-1.24C44.81,49,41,52.81,41,57.5S44.81,66,49.5,66S58,62.19,58,57.5V36h9V27H54z" />
+        android:fillColor="#0d1540"
+        android:pathData="M54,54m-38,0a38,38,0,1,0,76,0a38,38,0,1,0,-76,0"/>
+
+    <!-- Equalizer bars (5 bars, varying heights, vertically centred) combined into one path -->
+    <path
+        android:pathData="M28,41 A5,5,0,0,1,33,46 V61 A5,5,0,0,1,28,66 A5,5,0,0,1,23,61 V46 A5,5,0,0,1,28,41 Z
+                          M41,32 A5,5,0,0,1,46,37 V71 A5,5,0,0,1,41,76 A5,5,0,0,1,36,71 V37 A5,5,0,0,1,41,32 Z
+                          M54,24 A5,5,0,0,1,59,29 V80 A5,5,0,0,1,54,85 A5,5,0,0,1,49,80 V29 A5,5,0,0,1,54,24 Z
+                          M67,35 A5,5,0,0,1,72,40 V68 A5,5,0,0,1,67,73 A5,5,0,0,1,62,68 V40 A5,5,0,0,1,67,35 Z
+                          M80,44 A5,5,0,0,1,85,49 V60 A5,5,0,0,1,80,65 A5,5,0,0,1,75,60 V49 A5,5,0,0,1,80,44 Z">
+        <aapt:attr name="android:fillColor">
+            <gradient
+                android:type="linear"
+                android:startX="54"
+                android:startY="24"
+                android:endX="54"
+                android:endY="85"
+                android:startColor="#7eb8ff"
+                android:endColor="#8b3cf7"/>
+        </aapt:attr>
+    </path>
 </vector>

index.html

@@ -9,8 +9,8 @@
 <meta name="apple-mobile-web-app-status-bar-style" content="black-translucent">
 <meta name="apple-mobile-web-app-title" content="NovaSonic">
 <link rel="manifest" href="manifest.json">
-<link rel="icon" href="/icon.svg" type="image/svg+xml">
-<link rel="icon" href="/icon-192.png" type="image/png" sizes="192x192">
+<link rel="icon" href="%BASE_URL%icon.svg" type="image/svg+xml">
+<link rel="icon" href="%BASE_URL%icon-192.png" type="image/png" sizes="192x192">
 <link rel="apple-touch-icon" href="icon.svg">
 <title>NovaSonic</title>
 <link rel="preconnect" href="https://fonts.googleapis.com">

nginx.conf

@@ -35,6 +35,12 @@ server {
         add_header Access-Control-Allow-Origin "*";
     }
 
+    # /app/ alias so the reverse proxy prefix resolves static assets correctly
+    location /app/ {
+        alias /usr/share/nginx/html/;
+        try_files $uri /index.html;
+    }
+
     # SPA fallback
     location / {
         try_files $uri $uri/ /index.html;

vite.config.js

@@ -1,6 +1,7 @@
 import { defineConfig } from 'vite';
 
 export default defineConfig({
+  base: '/app/',
   build: {
     outDir: 'dist',
     assetsDir: 'assets',