Add PostgreSQL production backend to eliminate SQLite lock contention.

Support DATABASE_URL with connection pooling, pg_dump backups, SQLite migration script, and deploy_postgres.sh with docs.

Co-authored-by: Cursor <cursoragent@cursor.com>

app.py

@@ -9,7 +9,6 @@ from locale_fix import ensure_process_locale
 
 ensure_process_locale()
 
-import sqlite3
 import time
 import threading
 import requests
@@ -57,7 +56,7 @@ from kline_store import ensure_kline_tables
 from kline_stream import kline_hub, sse_format
 from kline_chart import generate_review_kline_chart, fetch_market_klines, MARKET_PERIODS
 from market import get_price as market_get_price, set_ths_refresh_token, get_quote_source_label
-from db_conn import connect_db
+from db_conn import OperationalError, connect_db, database_label, is_benign_migration_error, is_db_contention_error
 from admin_settings import save_admin_credentials
 from db_backup import (
     backup_dir,
@@ -292,10 +291,10 @@ def get_stats_data() -> dict:
             return data
         try:
             return refresh_stats_cache(conn, capital)
-        except sqlite3.OperationalError as exc:
-            if "locked" not in str(exc).lower():
+        except OperationalError as exc:
+            if not is_db_contention_error(exc):
                 raise
-            app.logger.warning("stats cache refresh locked, compute without save: %s", exc)
+            app.logger.warning("stats cache refresh contention, compute without save: %s", exc)
             return build_all_stats(conn, capital)
     finally:
         conn.close()
@@ -373,8 +372,9 @@ def init_db():
     for sql in migrations:
         try:
             c.execute(sql)
-        except sqlite3.OperationalError:
-            pass
+        except Exception as exc:
+            if not is_benign_migration_error(exc):
+                raise
     c.execute('''CREATE TABLE IF NOT EXISTS review_records
                  (id INTEGER PRIMARY KEY AUTOINCREMENT,
                   open_time TEXT, close_time TEXT,
@@ -426,8 +426,9 @@ def init_db():
     ):
         try:
             c.execute(sql)
-        except sqlite3.OperationalError:
-            pass
+        except Exception as exc:
+            if not is_benign_migration_error(exc):
+                raise
     ensure_kline_tables(conn)
     init_strategy_tables(conn)
     from risk.account_risk_lib import ensure_account_risk_schema
@@ -532,6 +533,7 @@ def sync_admin_from_env():
 
 
 init_db()
+app.logger.info("数据库: %s", database_label())
 
 
 def sync_ths_token():