feat: per-category greeting menu in bot config

Add a "Por Categoría" tab in the bot config UI where each permission
category (1, 2, 3) can be assigned its own greeting button menu.
When a user writes without an active context, the bot shows the menu
configured for their category instead of falling through to the global
greeting text.

NormalBot.process() now checks per_type[X].greeting_menu first, which
directly references a menu key and serves as both greeting and fallback
for that category. Fully backward-compatible with existing greeting_flow.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

public/index.php

@@ -410,6 +410,21 @@ $routes = [
         $aiProvider = trim($_POST['ai_provider'] ?? '');
         if ($aiProvider !== '') $config['ai_provider'] = $aiProvider;
 
+        // Per-category menus
+        $perTypeMenus = $_POST['per_type_menu'] ?? [];
+        $perType = [];
+        foreach ([1, 2, 3] as $cat) {
+            $mk = trim($perTypeMenus[$cat] ?? '');
+            if ($mk !== '') {
+                $perType[(string)$cat] = [
+                    'greeting_menu' => $mk,
+                    'greeting'      => '',
+                    'fallback'      => '',
+                ];
+            }
+        }
+        if (!empty($perType)) $config['per_type'] = $perType;
+
         // General
         $greeting = trim($_POST['greeting'] ?? '');
         if ($greeting !== '') $config['greeting'] = $greeting;