feat: Implement response variables support and comprehensive production audit (v2.1.8)

🚀 Major Features:
- Add response variables support to ask_question service
- Eliminate 255-character limitation for AI responses
- Enable direct data access in automations without sensors
- Prevent race conditions in parallel automations

🔧 Production Code Audit & Fixes:
- Enhanced resource management with context managers in api_client.py
- Fixed critical race conditions with asyncio.Semaphore implementation
- Improved file operations with atomic writes and corruption handling
- Enhanced error handling and logging security (removed sensitive data)
- Fixed _check_memory_available method placement in coordinator.py

🌐 Translation Updates (8 languages):
- Updated all translation files with response variables information
- Enhanced service descriptions in: en, ru, de, es, it, hi, sr, zh
- Added information about direct response capability
- Maintained consistency across all language files

📚 Documentation Enhancements:
- Added comprehensive Response Variables section to README
- Created advanced automation examples with response_variable usage
- Added migration guide from sensors to response variables
- Enhanced service documentation with response data structure
- Added practical examples for multi-step AI workflows

🔄 Service Improvements:
- Enhanced ask_question service to return structured response data
- Added comprehensive response schema in services.yaml
- Improved error handling with success/failure indicators
- Added metadata support (tokens, model, timestamp)

�� Version & Manifest:
- Bumped version to 2.1.8
- Maintained compatibility with existing integrations
- Updated service documentation

This release addresses GitHub issue #2 and significantly improves the integration's
production readiness while adding powerful new response variable functionality.

custom_components/ha_text_ai/translations/ru.json

@@ -98,7 +98,7 @@
   "services": {
     "ask_question": {
       "name": "Задать вопрос (HA Text AI)",
-      "description": "Отправить вопрос модели ИИ и получить подробный ответ. Ответ будет сохранен в истории разговора и может быть получен позже.",
+      "description": "Отправить вопрос модели ИИ и получить подробный ответ. Сервис теперь возвращает данные ответа напрямую, устраняя необходимость в отдельных текстовых сенсорах и ограничение в 255 символов. Ответ также будет сохранен в истории разговора.",
       "fields": {
         "instance": {
           "name": "Экземпляр",