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>

.claude/settings.json

@@ -2,7 +2,10 @@
   "permissions": {
     "allow": [
       "Bash(git -C /Users/serge/Develop/nnp-whisper-api-server log --oneline -10 --all)",
-      "Bash(git -C /Users/serge/Develop/nnp-whisper-api-server log --oneline main..cleanup/dead-code)"
+      "Bash(git -C /Users/serge/Develop/nnp-whisper-api-server log --oneline main..cleanup/dead-code)",
+      "Bash(ssh orange:*)",
+      "Bash(curl -s http://stt.ai.gray/health)",
+      "Bash(curl -s http://stt.ai.gray/v1/models)"
     ]
   }
 }