Implement full NFC-URL streaming architecture

- rc522: add NDEF URL reading via WUPA+cascade anticoll+SELECT+TLV parse
- AudioPlayer: route http:// URIs to esp_player_http_music_play()
- CacheManager: download URLs async to /sdcard/cache/{hash}.{ext}
- TagPlayerControl: NDEF URL → cache-or-stream; fallback to UID local mapping
- RFIDInterface: wire ndef_callback, expose combined uid+url callback
- WebInterface: add /api/info, /api/storage, /api/playback, /api/bluetooth
- BluetoothInterface: stub for A2DP speaker mode
- Networking: WiFi connect with 30s timeout instead of blocking forever
- main.cpp: re-enable WiFi + web server, fix init order, add CacheManager
- www/: full SPA — playback controls, device info, storage, BT pairing
- .gitmodules: switch rc522 submodule URL to HTTPS

https://claude.ai/code/session_01MhAnh68DPNnTjcKqjNYDmk

www/index.html

@@ -1,17 +1,59 @@
-<html>
-	<head>
-		<title>Kidsbox</title>	
-		<link rel="stylesheet" src="styles.css">
-	</head>
-	<body>
-		<h1>Hi, I'm a File!</h1>
+<!DOCTYPE html>
+<html lang="en">
+<head>
+  <meta charset="UTF-8">
+  <meta name="viewport" content="width=device-width, initial-scale=1">
+  <title>Kidsbox</title>
+  <link rel="stylesheet" href="styles.css">
+</head>
+<body>
+  <header>
+    <h1>&#127911; Kidsbox</h1>
+  </header>
 
-		<section class="rfid">
-			<h3>RFID-ID</h3>
-			<div class="rfid-id"></div>
-			<button class="rfid-refresh">refresh</button>
-		</section>
+  <main>
+    <section class="card" id="section-playback">
+      <h2>Now Playing</h2>
+      <div class="track-uri" id="track-uri">—</div>
+      <div class="playback-controls">
+        <button class="btn btn-primary"   id="btn-pause" disabled>Pause</button>
+        <button class="btn btn-secondary" id="btn-stop"  disabled>Stop</button>
+      </div>
+      <div class="volume-row">
+        <label for="volume-slider">Volume</label>
+        <input type="range" id="volume-slider" min="0" max="100" value="50">
+        <span id="volume-label">50</span>
+      </div>
+    </section>
 
-		<script src="main.js"></script>
-	</body>
-</html>
+    <section class="card" id="section-info">
+      <h2>Device Info</h2>
+      <table class="info-table">
+        <tr><th>IP Address</th><td id="info-ip">—</td></tr>
+        <tr><th>Status</th><td id="info-playing">—</td></tr>
+        <tr><th>Cache Used</th><td id="info-cache">—</td></tr>
+        <tr><th>Free Heap</th><td id="info-heap">—</td></tr>
+      </table>
+      <button class="btn btn-secondary" id="btn-refresh-info">Refresh</button>
+    </section>
+
+    <section class="card" id="section-storage">
+      <h2>Storage</h2>
+      <div class="storage-header">
+        <span id="storage-summary">Loading…</span>
+        <button class="btn btn-danger" id="btn-clear-cache">Clear All</button>
+      </div>
+      <ul class="cache-list" id="cache-list"></ul>
+    </section>
+
+    <section class="card" id="section-bluetooth">
+      <h2>Bluetooth Speaker</h2>
+      <p class="bt-status" id="bt-status">Disabled</p>
+      <button class="btn btn-secondary" id="btn-bt-toggle">Enable</button>
+      <p class="note">Pair your phone to play music through the Kidsbox speaker.</p>
+    </section>
+  </main>
+
+  <script src="main.js"></script>
+</body>
+</html>