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

fetch_history.py

@@ -1,10 +1,10 @@
 import requests
 import json
-import sqlite3
+import db
 import time
 from datetime import datetime, timezone
 
-DB_PATH = "_data/market_data.db"
+DB_PATH = os.environ.get("PG_CONN_STR", "postgresql://hyper:hyper@localhost:5432/hyper")
 URL = "https://api.hyperliquid.xyz/info"
 
 def fetch_historical_candles(coin, start_ms, end_ms, interval="1m"):
@@ -37,22 +37,10 @@ def fetch_historical_candles(coin, start_ms, end_ms, interval="1m"):
 
 def write_candles_to_db(coin, candles, interval="1m"):
     """Write candles to the database."""
-    table_name = coin + "_" + interval
-    conn = sqlite3.connect(DB_PATH)
-    cursor = conn.cursor()
-    # Ensure table exists
-    cursor.execute(f'''
-        CREATE TABLE IF NOT EXISTS "{table_name}" (
-            datetime_utc TEXT,
-            timestamp_ms INTEGER PRIMARY KEY,
-            open REAL,
-            high REAL,
-            low REAL,
-            close REAL,
-            volume REAL,
-            number_of_trades INTEGER
-        )
-    ''')
+    table_name = db.sanitize_table_name(coin, interval)
+    conn = db.get_connection()
+    db.create_candle_table(conn, table_name)
+    records = []
     for candle in candles:
         record = (
             datetime.fromtimestamp(candle['t'] / 1000, tz=timezone.utc).strftime('%Y-%m-%d %H:%M:%S'),
@@ -60,22 +48,16 @@ def write_candles_to_db(coin, candles, interval="1m"):
             candle.get('o'), candle.get('h'), candle.get('l'), candle.get('c'),
             candle.get('v'), candle.get('n')
         )
-        cursor.execute(f'''
-            INSERT OR REPLACE INTO "{table_name}" (datetime_utc, timestamp_ms, open, high, low, close, volume, number_of_trades)
-            VALUES (?, ?, ?, ?, ?, ?, ?, ?)
-        ''', record)
-    conn.commit()
+        records.append(record)
+    db.upsert_candles(conn, table_name, records)
     conn.close()
 
 def get_last_timestamp(coin):
     """Get the most recent timestamp from the database."""
-    table_name = coin + "_1m"
-    conn = sqlite3.connect(DB_PATH)
-    cursor = conn.cursor()
+    table_name = db.sanitize_table_name(coin, "1m")
+    conn = db.get_connection()
     try:
-        cursor.execute(f'SELECT MAX(timestamp_ms) FROM "{table_name}"')
-        result = cursor.fetchone()
-        return int(result[0]) if result and result[0] is not None else None
+        return db.get_last_timestamp(conn, table_name)
     except:
         return None
     finally: