feat: web server with REST API, captive portal, and management UI

Co-authored-by: Cursor <cursoragent@cursor.com>

data/index.html

@@ -0,0 +1,24 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <title>PaperColor</title>
+    <link rel="stylesheet" href="/style.css">
+</head>
+<body>
+    <nav>
+        <h1>PaperColor</h1>
+        <div id="nav-links">
+            <a href="#" data-page="dashboard" class="active">Dashboard</a>
+            <a href="#" data-page="albums">Albums</a>
+            <a href="#" data-page="slideshow">Slideshow</a>
+            <a href="#" data-page="display">Display</a>
+            <a href="#" data-page="device">Device</a>
+            <a href="#" data-page="firmware">Firmware</a>
+        </div>
+    </nav>
+    <main id="content"></main>
+    <script src="/app.js"></script>
+</body>
+</html>