Refactor logging, clean dead code, fix temp files and async tasks

- Replace f-string logging with % formatting throughout
- Fix create_temp_file: use mkstemp() instead of mkdtemp() (no leaked dirs)
- Add cleanup background thread and copy.deepcopy to AsyncTaskManager
- Fix transcribe_audio_async signature to accept transcription_service + params
- Use resample_poly instead of scipy_resample for better audio quality
- Remove unused validate_file/BinaryIO methods from FileValidator
- Add requests to requirements.txt
- Add error handling for pip install in server.sh
- Add __all__ and module docstrings to __init__.py files

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

app/infrastructure/log.py

@@ -91,7 +91,8 @@ class RequestLogger:
             return
         g.start_time = time.time()
         self.logger.info(
-            f"{request.method} {request.path} от {self._get_client_ip()}",
+            "%s %s от %s",
+            request.method, request.path, self._get_client_ip(),
             extra={"type": "request"}
         )
 
@@ -100,7 +101,8 @@ class RequestLogger:
             return response
         processing_time = time.time() - getattr(g, 'start_time', time.time())
         self.logger.info(
-            f"{response.status_code} за {processing_time:.3f} сек",
+            "%s за %.3f сек",
+            response.status_code, processing_time,
             extra={"type": "response"}
         )
         return response