add upload alert and documentation

static/app.js

@@ -1,3 +1,30 @@
+/*
+ RadChat Frontend (static/app.js)
+
+ Overview:
+ - Single-page application handling UI, signaling (WebSocket), and media (WebRTC).
+ - Uses a central CONFIG object (frozen) to define defaults for output, media, and connection.
+ - Manages:
+   * WebSocket connection lifecycle (reconnect, pings, presence)
+   * WebRTC peer connections (offers/answers/ICE, track management)
+   * UI state: users list, chat pane, emoji picker, file uploads, audio controls
+   * Permissions and device selection (planned for settings UI)
+
+ Key Endpoints (see backend):
+   - /ws: signaling channel (JSON messages matching message.go)
+   - /files: POST uploads; /files/{id}: GET downloads
+   - /check-username and /user-count auxiliary endpoints
+
+ Configuration:
+   - Adjust CONFIG.CONN.RTC_CONFIGURATION.iceServers to set STUN/TURN.
+   - For relay-only networks, consider setting iceTransportPolicy to "relay".
+
+ Notes:
+   - Keep JSON envelope fields in sync with message.go to avoid wire format drift.
+   - Avoid heavy DOM queries in hot paths; use cached selectors where possible.
+   - Large file; consider future modularization by feature (chat, rtc, ui, files).
+*/
+
 // ==================== CONFIGURATION ====================
 // noinspection HtmlUnknownTarget
 function Fz(obj) {
@@ -15,7 +42,7 @@ const CONFIG = Fz({
         NOISE_SUPPRESSION: true,
         LATENCY: 0.01,
         LATENCY_HINT: 'interactive',
-        SAMPLE_RATE: 64000,
+        SAMPLE_RATE: 96000,
         DEVICE_ID: 'default',
         SPEAKING_THRESHOLD: 10,
         SPEAKING_TIMEOUT: 500,
@@ -54,7 +81,7 @@ const CONFIG = Fz({
         CONNECTED_USER_LIMIT: 10,
         SAVE_RATE_THROTTLE: 1000,
         SYSTEM_MSG_DEFAULT_TIMEOUT: 5000,
-        FILE_UPLOAD_SIZE_LIMIT: 128 * (1024 * 1024),
+        FILE_UPLOAD_SIZE_LIMIT: 256 * (1024 * 1024),
     }
 });
 
@@ -441,17 +468,24 @@ class UIManager {
             formData.append('client_id', state.currentId)
 
             try {
+                // Uploading files system message
+                const alertMessage = ChatManager.addChatAlert('Uploading file(s)...', 'upload');
+
                 const response = await fetch('/files', {
                     method: 'POST',
                     body: formData
                 });
                 if (response.ok) {
+                    alertMessage.remove();
                     const data = await response.json();
                     console.log('Upload successful:', data);
                 } else {
+                    alertMessage.remove();
+                    ChatManager.addChatAlert(`Upload failed: ${error}`, 'upload_failure', 3000);
                     console.error('Upload failed:', response.statusText);
                 }
             } catch (error) {
+                ChatManager.addChatAlert(`Upload failed: ${error}`, 'upload_failure', 3000);
                 console.error('Upload error:', error);
             }
         }, { once: true });
@@ -1634,7 +1668,7 @@ class ChatManager {
         UIManager.scrollChatToBottom();
         console.log('Added chat message from:', data.username, 'message:', message);
     }
-    static addChatAlert(message, type, timeout) {
+    static addChatAlert(message, type, timeout)  {
         const chatMessages = $id('chat-messages');
         if (!chatMessages) return;
         const alertEl = document.createElement('div');
@@ -1659,6 +1693,7 @@ class ChatManager {
         chatMessages.appendChild(alertEl);
         UIManager.scrollChatToBottom();
         console.log('📢 Added chat alert:', message);
+        return alertEl;
     }
 
     static deleteMessage(messageId) {