refactor(bot-detector): extract monolith into modular package

Split bot_detector.py (~1982 lines) into 10 focused modules:
- config.py: all configuration constants and optional imports
- log.py: logging utilities (log_info, log_decision, append_training_history)
- infra.py: ClickHouse client, health check HTTP server, shutdown
- browser.py: multifactorial browser identification (5 axes)
- scoring.py: drift detection, feature validation, SHAP, clustering
- models.py: EIF, Autoencoder, XGBoost model management
- preprocessing.py: data preprocessing and feature list definitions
- pipeline.py: core semi-supervised scoring loop
- cycle.py: main analysis cycle orchestration
- __main__.py: entry point with startup banner

Update Dockerfile to copy package directory and use python -m bot_detector.

All 36 existing tests pass unchanged.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

services/bot-detector/bot_detector/Dockerfile

@@ -13,6 +13,6 @@ RUN pip install --no-cache-dir /app/shared/ja4_common/
 COPY services/bot-detector/bot_detector/requirements.txt .
 RUN pip install --no-cache-dir -r requirements.txt
 
-COPY services/bot-detector/bot_detector/bot_detector.py .
+COPY services/bot-detector/bot_detector/ ./bot_detector/
 
-CMD ["python", "bot_detector.py"]
+CMD ["python", "-m", "bot_detector"]