design: change to minimalistic and clean light theme

- Replace Matrix/terminal dark theme with modern light design
- Update Tailwind config with clean, professional color palette
- Change from monospace to Inter sans-serif font
- Update chart styling to use white background with subtle grids
- Remove glow effects and neon colors from buttons and UI
- Update color picker with better color options
- Improve sidebar spacing and typography
- Update annotation badges with softer colors
- Change scrollbar styling to match light theme

src/app/globals.css

@@ -4,25 +4,25 @@
 
 @layer base {
   :root {
-    --background: 120 100% 4%;
-    --foreground: 120 100% 50%;
-    --card: 120 100% 6%;
-    --card-foreground: 120 100% 50%;
-    --popover: 120 100% 4%;
-    --popover-foreground: 120 100% 50%;
-    --primary: 120 100% 50%;
-    --primary-foreground: 120 100% 4%;
-    --secondary: 120 100% 8%;
-    --secondary-foreground: 120 100% 50%;
-    --muted: 120 100% 10%;
-    --muted-foreground: 120 100% 40%;
-    --accent: 120 100% 50%;
-    --accent-foreground: 120 100% 4%;
-    --destructive: 348 100% 50%;
-    --destructive-foreground: 120 100% 4%;
-    --border: 120 100% 10%;
-    --input: 120 100% 8%;
-    --ring: 120 100% 50%;
+    --background: 0 0% 100%;
+    --foreground: 222 47% 11%;
+    --card: 0 0% 100%;
+    --card-foreground: 222 47% 11%;
+    --popover: 0 0% 100%;
+    --popover-foreground: 222 47% 11%;
+    --primary: 221 83% 53%;
+    --primary-foreground: 210 40% 98%;
+    --secondary: 210 40% 96%;
+    --secondary-foreground: 222 47% 11%;
+    --muted: 210 40% 96%;
+    --muted-foreground: 215 16% 47%;
+    --accent: 210 40% 96%;
+    --accent-foreground: 222 47% 11%;
+    --destructive: 0 84% 60%;
+    --destructive-foreground: 210 40% 98%;
+    --border: 214 32% 91%;
+    --input: 214 32% 91%;
+    --ring: 221 83% 53%;
     --radius: 0.5rem;
   }
 }
@@ -32,14 +32,14 @@
     @apply border-border;
   }
   body {
-    @apply bg-background text-foreground;
-    font-family: 'JetBrains Mono', 'Fira Code', 'Courier New', monospace;
+    @apply bg-background text-foreground antialiased;
+    font-family: 'Inter', system-ui, -apple-system, sans-serif;
   }
 }
 
 @layer base {
   ::selection {
-    @apply bg-matrix/40 text-matrix;
+    @apply bg-primary/20 text-foreground;
   }
   
   ::-webkit-scrollbar {
@@ -47,10 +47,10 @@
   }
   
   ::-webkit-scrollbar-track {
-    @apply bg-matrixDark;
+    @apply bg-muted;
   }
   
   ::-webkit-scrollbar-thumb {
-    @apply bg-matrix rounded;
+    @apply bg-border hover:bg-muted-foreground/30 rounded;
   }
 }

src/app/page.tsx

@@ -87,30 +87,33 @@ export default function Home() {
   }, [selectedLabelId]);
 
   return (
-    <div className="flex h-screen">
+    <div className="flex h-screen bg-background">
       {/* Sidebar */}
-      <aside className="w-64 flex-shrink-0 flex flex-col border-r border-border">
-        <div className="p-4 border-b border-border">
-          <h1 className="text-xl font-bold">Candle Annotator</h1>
+      <aside className="w-72 flex-shrink-0 flex flex-col border-r border-border bg-card">
+        <div className="p-6 border-b border-border">
+          <h1 className="text-2xl font-semibold text-foreground">Candle Annotator</h1>
+          <p className="text-sm text-muted-foreground mt-1">Chart annotation tool</p>
         </div>
-        <div className="p-4">
+        <div className="p-6">
           <FileUpload onUploadSuccess={handleUploadSuccess} />
         </div>
-        <Toolbox
-          activeTool={activeTool}
-          onToolChange={setActiveTool}
-          onExport={handleExport}
-          selectedColor={selectedColor}
-          onColorChange={setSelectedColor}
-          annotations={annotations}
-          selectedLabelId={selectedLabelId}
-          onLabelSelect={handleLabelSelect}
-          onLabelDelete={handleLabelDelete}
-        />
+        <div className="px-6 pb-6">
+          <Toolbox
+            activeTool={activeTool}
+            onToolChange={setActiveTool}
+            onExport={handleExport}
+            selectedColor={selectedColor}
+            onColorChange={setSelectedColor}
+            annotations={annotations}
+            selectedLabelId={selectedLabelId}
+            onLabelSelect={handleLabelSelect}
+            onLabelDelete={handleLabelDelete}
+          />
+        </div>
       </aside>
 
       {/* Main chart area */}
-      <main className="flex-1 relative">
+      <main className="flex-1 relative bg-background">
         <CandleChart
           ref={chartRef}
           activeTool={activeTool}