build: establecer DATA_DIR por defecto y declarar volumen /app/data

Co-authored-by: aider (openrouter/openai/gpt-5) <aider@aider.chat>

Dockerfile

@@ -4,6 +4,8 @@ FROM oven/bun:1.1 as base
 # Install basic debugging tools
 RUN apt-get update && apt-get install -y curl netcat sqlite3
 WORKDIR /app
+# Default data dir for SQLite; can be overridden by DB_PATH at runtime (DB_PATH has priority)
+ENV DATA_DIR=/app/data
 
 # Create data directory with proper permissions
 RUN mkdir -p /app/data && chown -R bun:bun /app/data
@@ -22,6 +24,8 @@ HEALTHCHECK --start-period=30s --interval=30s --timeout=3s --retries=3 \
 
 # Server runs on port from environment variable
 EXPOSE ${PORT:-3007}
+# Declare volume for persistent data by default
+VOLUME ["/app/data"]
 
 # Make script executable
 COPY startup.sh ./