Add SDK persistence and configurable edge location

- Add external SDK installation (wp-content/twilio-sdk/) that survives
  WordPress plugin updates
- Add install-twilio-sdk-external.sh script for external SDK setup
- Update SDK loading to check external location first, internal fallback
- Add post-update detection hook to warn if SDK was deleted
- Add configurable Twilio Edge Location setting (default: roaming)
- Fix US calls failing due to hardcoded Sydney edge location

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

twilio-wp-plugin.php

@@ -20,6 +20,8 @@ define('TWP_DB_VERSION', '1.6.2'); // Track database version separately
 define('TWP_PLUGIN_DIR', plugin_dir_path(__FILE__));
 define('TWP_PLUGIN_URL', plugin_dir_url(__FILE__));
 define('TWP_PLUGIN_BASENAME', plugin_basename(__FILE__));
+// External SDK location - survives plugin updates (wp-content/twilio-sdk/)
+define('TWP_EXTERNAL_SDK_DIR', dirname(dirname(TWP_PLUGIN_DIR)) . '/twilio-sdk/');
 
 /**
  * Plugin activation hook
@@ -31,17 +33,27 @@ function twp_activate() {
 
 /**
  * Check if Twilio SDK is installed and show admin notice if not
+ * Checks external location first (survives plugin updates), then internal fallback
  */
 function twp_check_sdk_installation() {
-    $autoloader_path = TWP_PLUGIN_DIR . 'vendor/autoload.php';
     $sdk_installed = false;
-    
-    if (file_exists($autoloader_path)) {
-        // Try to load autoloader and check for classes
-        require_once $autoloader_path;
+
+    // Priority 1: Check external SDK location (survives plugin updates)
+    $external_autoloader = TWP_EXTERNAL_SDK_DIR . 'autoload.php';
+    if (file_exists($external_autoloader)) {
+        require_once $external_autoloader;
         $sdk_installed = class_exists('Twilio\Rest\Client');
     }
-    
+
+    // Priority 2: Fall back to internal vendor directory
+    if (!$sdk_installed) {
+        $internal_autoloader = TWP_PLUGIN_DIR . 'vendor/autoload.php';
+        if (file_exists($internal_autoloader)) {
+            require_once $internal_autoloader;
+            $sdk_installed = class_exists('Twilio\Rest\Client');
+        }
+    }
+
     if (!$sdk_installed) {
         add_action('admin_notices', 'twp_sdk_missing_notice');
     }
@@ -55,10 +67,12 @@ function twp_sdk_missing_notice() {
     <div class="notice notice-error is-dismissible">
         <h3>Twilio WordPress Plugin - SDK Required</h3>
         <p><strong>The Twilio PHP SDK is required for this plugin to work.</strong></p>
-        <p>To install the SDK, run this command in your plugin directory:</p>
+        <p><strong>Recommended:</strong> Install SDK to external location (survives plugin updates):</p>
+        <code>chmod +x install-twilio-sdk-external.sh && ./install-twilio-sdk-external.sh</code>
+        <p style="margin-top: 10px;"><strong>Alternative:</strong> Install SDK inside plugin folder:</p>
         <code>chmod +x install-twilio-sdk.sh && ./install-twilio-sdk.sh</code>
-        <p>Or install via Composer: <code>composer install</code></p>
-        <p><em>Plugin path: <?php echo TWP_PLUGIN_DIR; ?></em></p>
+        <p style="margin-top: 10px;"><em>Plugin path: <?php echo esc_html(TWP_PLUGIN_DIR); ?></em></p>
+        <p><em>External SDK path: <?php echo esc_html(TWP_EXTERNAL_SDK_DIR); ?></em></p>
     </div>
     <?php
 }
@@ -126,6 +140,52 @@ function twp_deactivate() {
 register_activation_hook(__FILE__, 'twp_activate');
 register_deactivation_hook(__FILE__, 'twp_deactivate');
 
+/**
+ * Check SDK status after plugin updates
+ * Shows warning if SDK was deleted during update and external SDK not available
+ */
+function twp_check_sdk_after_update($upgrader_object, $options) {
+    // Only run for plugin updates
+    if ($options['action'] !== 'update' || $options['type'] !== 'plugin') {
+        return;
+    }
+
+    // Check if this plugin was updated
+    $updated_plugins = isset($options['plugins']) ? $options['plugins'] : array();
+    if (!in_array(TWP_PLUGIN_BASENAME, $updated_plugins)) {
+        return;
+    }
+
+    // Check if SDK is available
+    $external_sdk = file_exists(TWP_EXTERNAL_SDK_DIR . 'autoload.php');
+    $internal_sdk = file_exists(TWP_PLUGIN_DIR . 'vendor/autoload.php');
+
+    if (!$external_sdk && !$internal_sdk) {
+        // Set a transient to show warning on next admin page load
+        set_transient('twp_sdk_update_warning', true, 60 * 5);
+    }
+}
+add_action('upgrader_process_complete', 'twp_check_sdk_after_update', 10, 2);
+
+/**
+ * Show SDK update warning
+ */
+function twp_show_sdk_update_warning() {
+    if (get_transient('twp_sdk_update_warning')) {
+        delete_transient('twp_sdk_update_warning');
+        ?>
+        <div class="notice notice-warning is-dismissible">
+            <h3>Twilio WordPress Plugin - SDK Reinstall Required</h3>
+            <p><strong>The plugin was updated and the Twilio SDK needs to be reinstalled.</strong></p>
+            <p>To prevent this in the future, install the SDK to the external location:</p>
+            <code>cd <?php echo esc_html(TWP_PLUGIN_DIR); ?> && ./install-twilio-sdk-external.sh</code>
+            <p style="margin-top: 10px;">The external SDK at <code><?php echo esc_html(TWP_EXTERNAL_SDK_DIR); ?></code> survives plugin updates.</p>
+        </div>
+        <?php
+    }
+}
+add_action('admin_notices', 'twp_show_sdk_update_warning');
+
 /**
  * Core plugin class
  */