ui: polish header and user panel with dropdown + profile pic support & file list adjustments

public/api/profile/uploadPicture.php

@@ -0,0 +1,17 @@
+<?php
+require_once __DIR__ . '/../../../config/config.php';
+require_once PROJECT_ROOT . '/src/controllers/UserController.php';
+
+// Always JSON, even on PHP notices
+header('Content-Type: application/json');
+
+try {
+    $userController = new UserController();
+    $userController->uploadPicture();
+} catch (\Throwable $e) {
+    http_response_code(500);
+    echo json_encode([
+      'success' => false,
+      'error'   => 'Exception: ' . $e->getMessage()
+    ]);
+}