Update log retention period to 30 days in custom logger and add comment on log cleanup mechanism.

Dockerfile

@@ -0,0 +1,37 @@
+# syntax=docker/dockerfile:1
+
+# Use a lightweight Python image
+FROM python:3.11-slim
+
+# Prevent Python from writing .pyc files and enable unbuffered logs
+ENV PYTHONDONTWRITEBYTECODE=1 \
+    PYTHONUNBUFFERED=1
+
+# Install system dependencies (if required by Python packages)
+RUN apt-get update \
+    && apt-get install -y --no-install-recommends build-essential \
+    && rm -rf /var/lib/apt/lists/*
+
+# Set working directory
+WORKDIR /app
+
+# Create non-root user
+RUN useradd -m appuser \
+    && chown -R appuser:appuser /app
+
+# Install Python dependencies first for better layer caching
+COPY requirements.txt ./
+RUN pip install --no-cache-dir -r requirements.txt
+
+# Copy project files
+COPY . .
+
+# Ensure runtime directories exist and are writable
+RUN mkdir -p logs database \
+    && chown -R appuser:appuser /app
+
+# Switch to non-root user
+USER appuser
+
+# Run the bot
+CMD ["python", "run_helper.py"]