feat: add varied microphone array presets

apps/acoustic-camera/index.html

@@ -3,7 +3,7 @@
   <head>
     <meta charset="UTF-8" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
-    <meta name="description" content="192채널 WebGPU acoustic camera simulator" />
+    <meta name="description" content="다중 채널 CPU·WebGPU acoustic camera simulator" />
     <title>Acoustic Camera · micarrsim</title>
     <link rel="stylesheet" href="/packages/ui/app-shell.css" />
     <link rel="stylesheet" href="/apps/acoustic-camera/styles.css" />
@@ -52,7 +52,28 @@
 
             <div class="array-card">
               <div class="array-heading"><div><span class="compact-label">MIC ARRAY</span><h3 id="array-title">배열</h3></div><strong id="microphone-count">— ch</strong></div>
-              <label class="field"><span>배열 선택</span><select id="array-preset"><option value="rectangular-16x12">16×12 rectangular · 기준</option><option value="fermat-spiral-192">Fermat spiral · 비교</option><option value="custom">불러온 Array JSON</option></select></label>
+              <label class="field">
+                <span>배열 선택</span>
+                <select id="array-preset">
+                  <optgroup label="기준 배열">
+                    <option value="rectangular-16x12">16×12 rectangular · 192 ch / 0.45 m</option>
+                    <option value="fermat-spiral-192">Fermat spiral · 192 ch / Ø 0.45 m</option>
+                  </optgroup>
+                  <optgroup label="채널 수 비교 · 0.45 m">
+                    <option value="rectangular-2x2-450mm">2×2 sparse · 4 ch</option>
+                    <option value="rectangular-4x3-450mm">4×3 sparse · 12 ch</option>
+                    <option value="rectangular-8x6-450mm">8×6 · 48 ch</option>
+                    <option value="rectangular-24x16-450mm">24×16 dense · 384 ch</option>
+                  </optgroup>
+                  <optgroup label="물리 크기 비교 · 192 ch">
+                    <option value="rectangular-16x12-compact">16×12 compact · 0.12 m</option>
+                    <option value="rectangular-16x12-large">16×12 large · 1.20 m</option>
+                  </optgroup>
+                  <optgroup label="사용자 배열">
+                    <option value="custom">불러온 Array JSON</option>
+                  </optgroup>
+                </select>
+              </label>
               <details class="inline-details" id="array-details">
                 <summary>배열 미리보기와 좌표 정보</summary>
                 <canvas id="array-canvas" aria-label="마이크 배열 평면도"></canvas>