feat: multi-provider AI with per-company override and Claude support

- Global settings: custom AI panel with OpenAI/Gemini/Claude each with
  API key, model selector, and live test-connection button (no save needed)
- Per-company IA tab: same three providers + fallback to global when empty
- AiBot: reads per-company config_json first, falls back to env() global
- Added callClaude() for Anthropic Messages API
- More OpenAI models: gpt-4.1, gpt-4.1-mini
- test-ai endpoint: accepts provider/api_key/model from POST for live test

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

setup/migrate.php

@@ -201,6 +201,8 @@ $seedSettings = [
     'openai_model'                     => 'gpt-4o-mini',
     'gemini_api_key'                   => '',
     'gemini_model'                     => 'gemini-2.5-flash',
+    'claude_api_key'                   => '',
+    'claude_model'                     => 'claude-haiku-4-5',
     'ai_max_tokens'                    => '500',
     'ai_default_prompt'                => 'Eres un asistente virtual de Palmas360. Responde de forma amable y profesional.',
 ];