feat: add zap split preset buttons

- Added 4 preset buttons: Default, Generous, Selfless, and Boris 🧡
- Default: 50/2.1/50 (You: 49%, Author: 49%, Boris: 2%)
- Generous: 5/10/75 (You: 6%, Author: 83%, Boris: 11%)
- Selfless: 1/19/80 (You: 1%, Author: 80%, Boris: 19%)
- Boris 🧡: 10/80/10 (You: 10%, Author: 10%, Boris: 80%)
- One-click setup for common zap split configurations
- Hover tooltips show actual percentage splits

src/components/Settings/ZapSettings.tsx

@@ -17,10 +17,52 @@ const ZapSettings: React.FC<ZapSettingsProps> = ({ settings, onUpdate }) => {
   const borisPercentage = totalWeight > 0 ? (borisWeight / totalWeight) * 100 : 0
   const authorPercentage = totalWeight > 0 ? (authorWeight / totalWeight) * 100 : 0
 
+  const applyPreset = (preset: { highlighter: number; boris: number; author: number }) => {
+    onUpdate({
+      zapSplitHighlighterWeight: preset.highlighter,
+      zapSplitBorisWeight: preset.boris,
+      zapSplitAuthorWeight: preset.author,
+    })
+  }
+
   return (
     <div className="settings-section">
       <h3 className="section-title">Zap Splits</h3>
       
+      <div className="setting-group">
+        <label className="setting-label">Presets</label>
+        <div className="zap-preset-buttons">
+          <button
+            onClick={() => applyPreset({ highlighter: 50, boris: 2.1, author: 50 })}
+            className="zap-preset-btn"
+            title="You: 49%, Author: 49%, Boris: 2%"
+          >
+            Default
+          </button>
+          <button
+            onClick={() => applyPreset({ highlighter: 5, boris: 10, author: 75 })}
+            className="zap-preset-btn"
+            title="You: 6%, Author: 83%, Boris: 11%"
+          >
+            Generous
+          </button>
+          <button
+            onClick={() => applyPreset({ highlighter: 1, boris: 19, author: 80 })}
+            className="zap-preset-btn"
+            title="You: 1%, Author: 80%, Boris: 19%"
+          >
+            Selfless
+          </button>
+          <button
+            onClick={() => applyPreset({ highlighter: 10, boris: 80, author: 10 })}
+            className="zap-preset-btn"
+            title="You: 10%, Author: 10%, Boris: 80%"
+          >
+            Boris 🧡
+          </button>
+        </div>
+      </div>
+      
       <div className="setting-group">
         <label className="setting-label">Your Share</label>
         <div className="zap-split-container">

src/index.css

@@ -2088,6 +2088,36 @@ body {
   text-align: left;
 }
 
+.zap-preset-buttons {
+  display: flex;
+  gap: 0.5rem;
+  flex-wrap: wrap;
+}
+
+.zap-preset-btn {
+  padding: 0.5rem 1rem;
+  background: #2a2a2a;
+  border: 1px solid #444;
+  border-radius: 6px;
+  color: #ccc;
+  font-size: 0.9rem;
+  cursor: pointer;
+  transition: all 0.2s;
+  flex: 1;
+  min-width: 80px;
+}
+
+.zap-preset-btn:hover {
+  background: #333;
+  border-color: #646cff;
+  color: white;
+  transform: translateY(-1px);
+}
+
+.zap-preset-btn:active {
+  transform: translateY(0);
+}
+
 .settings-footer {
   display: flex;
   justify-content: flex-start;