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

docker-compose.yml

@@ -0,0 +1,42 @@
+version: "3.8"
+
+services:
+  postgres:
+    image: postgres:15-alpine
+    container_name: hyper_pg
+    restart: unless-stopped
+    environment:
+      POSTGRES_DB: hyper
+      POSTGRES_USER: hyper
+      POSTGRES_PASSWORD: ${POSTGRES_PASSWORD}
+    volumes:
+      - pg_data:/var/lib/postgresql/data
+      - ./postgres/postgresql.conf:/etc/postgresql/postgresql.conf
+    command: postgres -c config_file=/etc/postgresql/postgresql.conf
+    ports:
+      - "5432:5432"
+    networks:
+      - hyper_net
+
+  data-collector:
+    build: .
+    container_name: hyper_data
+    restart: unless-stopped
+    depends_on:
+      - postgres
+    env_file:
+      - .env.docker
+    volumes:
+      - ./_data:/app/_data
+      - ./_logs:/app/_logs
+      - ./secrets:/app/secrets
+      - /volume1/docker/hyper/backups:/backups
+    networks:
+      - hyper_net
+
+volumes:
+  pg_data:
+
+networks:
+  hyper_net:
+    driver: bridge