feat: auto-generate coingecko.json on first run

Added logic to check for the existence of 'coingecko.json' and generate it by executing 'coingecko.php' if it doesn't exist. This ensures that the necessary data file is available on first run, preventing potential errors or missing data.

index.php

@@ -9,6 +9,12 @@ $currentUrl = $protocol . $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'];
 $parentUrl = dirname($currentUrl);
 
 // Get currency data from JSON
+if (!file_exists('coingecko.json')) {
+    // Special case: First run.
+    exec('php coingecko.php');
+    sleep(1);
+}
+
 $api_cg = json_decode(file_get_contents('coingecko.json'), true);
 
 // Configuration file