Migrate data pipeline from SQLite to PostgreSQL + Docker setup

- Add db.py PostgreSQL abstraction layer (connection, upsert, table mgmt)
- Replace sqlite3 with psycopg2 in: live_candle_fetcher, resampler,
  data_fetcher, fetch_history, import_csv, indicators, base_strategy
- Sanitize table names (colons -> underscores) for PostgreSQL compat
- Replace INSERT OR REPLACE with ON CONFLICT upserts
- Replace pandas to_sql() with batch upsert_candles()
- Add scripts: resampler_loop, gap_detector, backup_runner, cron_scheduler
- Add migrate_sqlite_to_pg.py for one-time data migration
- Add Dockerfile, docker-compose.yml, supervisord.conf
- Add postgres/postgresql.conf tuned for 4GB RAM (Synology DS1513+)
- Add .dockerignore, .env.docker.example, secrets template
- Update requirements.txt (psycopg2-binary), .gitignore
- Add MIGRATION_PLAN.md with full plan and todo list

scripts/backup_runner.py

@@ -0,0 +1,74 @@
+#!/usr/bin/env python3
+"""
+Backup Runner
+
+Creates a daily pg_dump backup of the PostgreSQL database, compresses it,
+and retains only the last 7 days of backups.
+
+Designed to run as a periodic cron job (daily) inside the Docker container.
+Backups are written to /backups which is mounted to a Synology shared folder.
+"""
+
+import argparse
+import logging
+import os
+import subprocess
+from datetime import datetime, timedelta
+
+from logging_utils import setup_logging
+
+BACKUP_DIR = "/backups"
+RETENTION_DAYS = 7
+
+
+def run_backup():
+    """Run pg_dump and compress the output."""
+    today = datetime.now().strftime("%Y%m%d")
+    backup_file = os.path.join(BACKUP_DIR, f"hyper_{today}.sql.gz")
+
+    os.makedirs(BACKUP_DIR, exist_ok=True)
+
+    logging.info(f"Starting backup to {backup_file}")
+
+    cmd = f"pg_dump -h postgres -U hyper hyper | gzip > {backup_file}"
+    result = subprocess.run(cmd, shell=True, capture_output=True, text=True)
+
+    if result.returncode == 0:
+        file_size = os.path.getsize(backup_file)
+        logging.info(f"Backup completed: {backup_file} ({file_size:,} bytes)")
+    else:
+        logging.error(f"Backup failed: {result.stderr}")
+        if os.path.exists(backup_file):
+            os.remove(backup_file)
+
+    cleanup_old_backups()
+
+
+def cleanup_old_backups():
+    """Delete backup files older than RETENTION_DAYS."""
+    cutoff = datetime.now() - timedelta(days=RETENTION_DAYS)
+
+    if not os.path.exists(BACKUP_DIR):
+        return
+
+    for filename in os.listdir(BACKUP_DIR):
+        if filename.startswith("hyper_") and filename.endswith(".sql.gz"):
+            filepath = os.path.join(BACKUP_DIR, filename)
+            mtime = datetime.fromtimestamp(os.path.getmtime(filepath))
+            if mtime < cutoff:
+                os.remove(filepath)
+                logging.info(f"Deleted old backup: {filename}")
+
+
+def main():
+    parser = argparse.ArgumentParser(description="Run PostgreSQL backup.")
+    parser.add_argument("--log-level", default="normal", choices=['off', 'normal', 'debug'])
+    args = parser.parse_args()
+
+    setup_logging(args.log_level, 'BackupRunner')
+
+    run_backup()
+
+
+if __name__ == "__main__":
+    main()