Fix exit button responsiveness and progress bar accuracy

Exit button:
- Check for Back button inside handleClient loop (every 64 iterations)
- Makes exit much more responsive during uploads

Progress bar:
- Cap local progress at 95% while sending chunks
- Show 100% only when server confirms DONE
- Prevents progress sitting at 100% while server still writing

src/activities/network/CrossPointWebServerActivity.cpp

@@ -322,19 +322,24 @@ void CrossPointWebServerActivity::loop() {
       constexpr int MAX_ITERATIONS = 500;
       for (int i = 0; i < MAX_ITERATIONS && webServer->isRunning(); i++) {
         webServer->handleClient();
-        // Reset watchdog every 32 iterations, yield every 64
-        // Tight loop with minimal yielding for maximum speed
+        // Reset watchdog every 32 iterations
         if ((i & 0x1F) == 0x1F) {
           esp_task_wdt_reset();
         }
+        // Yield and check for exit button every 64 iterations
         if ((i & 0x3F) == 0x3F) {
           yield();
+          // Check for exit button inside loop for responsiveness
+          if (mappedInput.wasPressed(MappedInputManager::Button::Back)) {
+            onGoBack();
+            return;
+          }
         }
       }
       lastHandleClientTime = millis();
     }
 
-    // Handle exit on Back button
+    // Handle exit on Back button (also check outside loop)
     if (mappedInput.wasPressed(MappedInputManager::Button::Back)) {
       onGoBack();
       return;

src/network/html/FilesPage.html

@@ -874,8 +874,12 @@ function uploadFileWebSocket(file, onProgress, onComplete, onError) {
             ws.send(buffer);
             offset += chunkSize;
 
-            // Update local progress
-            if (onProgress) onProgress(offset, totalSize);
+            // Update local progress - cap at 95% since server still needs to write
+            // Final 100% shown when server confirms DONE
+            if (onProgress) {
+              const cappedOffset = Math.min(offset, Math.floor(totalSize * 0.95));
+              onProgress(cappedOffset, totalSize);
+            }
           }
 
           sendingChunks = false;
@@ -891,6 +895,8 @@ function uploadFileWebSocket(file, onProgress, onComplete, onError) {
         // (local progress is smoother, server progress causes jumping)
         console.log('[WS] Server progress:', msg);
       } else if (msg === 'DONE') {
+        // Show 100% when server confirms completion
+        if (onProgress) onProgress(file.size, file.size);
         ws.close();
         if (onComplete) onComplete();
         resolve();