Fix AI tab save: dedicated AJAX endpoint /save-ai

Instead of relying on the native HTML form (which couldn't reliably
isolate AI fields), the IA tab now uses an AJAX call identical to
save-per-type. The new /admin/bot-config/save-ai endpoint only
reads and merges AI fields into config_json, preserving menus/flows.

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

public/index.php

@@ -587,6 +587,53 @@ $routes = [
         exit;
     })()],
 
+    // ─── Admin: guardar solo campos IA (endpoint separado) ───────────────────
+    ['POST', '/admin/bot-config/save-ai', fn() => (function () {
+        SessionAuth::require();
+        header('Content-Type: application/json; charset=utf-8');
+        $companyId = (int)($_POST['company_id'] ?? 0);
+        if ($companyId === 0) { echo json_encode(['ok' => false, 'error' => 'missing company_id']); exit; }
+
+        $company = CompanyRepository::findById($companyId);
+        if (!$company) { echo json_encode(['ok' => false, 'error' => 'not found']); exit; }
+
+        $config = json_decode($company['config_json'] ?? '{}', true) ?: [];
+
+        $aiProvider = trim($_POST['ai_provider'] ?? '');
+        if ($aiProvider !== '') $config['ai_provider'] = $aiProvider; else unset($config['ai_provider']);
+
+        $aiModel = trim($_POST['ai_model'] ?? '');
+        if ($aiModel !== '') $config['ai_model'] = $aiModel;
+
+        $aiTemp = trim($_POST['ai_temperature'] ?? '');
+        if ($aiTemp !== '') $config['ai_temperature'] = (float)$aiTemp;
+
+        $aiPrompt = trim($_POST['ai_prompt'] ?? '');
+        $config['ai_prompt'] = $aiPrompt;
+
+        $config['ai_for_media'] = isset($_POST['ai_for_media']);
+        $config['nlu']          = isset($_POST['nlu']);
+
+        $openaiKey = trim($_POST['openai_api_key'] ?? '');
+        if ($openaiKey !== '') $config['openai_api_key'] = $openaiKey;
+
+        $geminiKey = trim($_POST['gemini_api_key'] ?? '');
+        if ($geminiKey !== '') $config['gemini_api_key'] = $geminiKey;
+
+        $geminiModel = trim($_POST['gemini_model'] ?? '');
+        if ($geminiModel !== '') $config['gemini_model'] = $geminiModel;
+
+        $claudeKey = trim($_POST['claude_api_key'] ?? '');
+        if ($claudeKey !== '') $config['claude_api_key'] = $claudeKey;
+
+        $claudeModel = trim($_POST['claude_model'] ?? '');
+        if ($claudeModel !== '') $config['claude_model'] = $claudeModel;
+
+        CompanyRepository::save(['id' => $companyId, 'config_json' => json_encode($config, JSON_UNESCAPED_UNICODE)]);
+        echo json_encode(['ok' => true]);
+        exit;
+    })()],
+
     // ─── Admin: guardar per_type por categoría (endpoint separado) ───────────
     ['POST', '/admin/bot-config/save-per-type', fn() => (function () {
         SessionAuth::require();