fix: remove SQLite fallback code from db_engine.py (#70)

Removes DATABASE_TYPE conditional entirely. PostgreSQL is now the only
supported backend. Moves PooledPostgresqlDatabase import to top-level
and raises RuntimeError at startup if POSTGRES_PASSWORD is unset,
preventing silent misconnection with misleading errors.

Closes #70

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/db_engine.py

@@ -8,39 +8,29 @@ from typing import Literal, List, Optional
 from pandas import DataFrame
 from peewee import *
 from peewee import ModelSelect
+from playhouse.pool import PooledPostgresqlDatabase
 from playhouse.shortcuts import model_to_dict
 
-# Database configuration - supports both SQLite and PostgreSQL
+_postgres_password = os.environ.get("POSTGRES_PASSWORD")
-DATABASE_TYPE = os.environ.get("DATABASE_TYPE", "sqlite")
+if _postgres_password is None:
-
+    raise RuntimeError(
-if DATABASE_TYPE.lower() == "postgresql":
+        "POSTGRES_PASSWORD environment variable is not set. "
-    from playhouse.pool import PooledPostgresqlDatabase
+        "This variable is required when DATABASE_TYPE=postgresql."
-
-    _postgres_password = os.environ.get("POSTGRES_PASSWORD")
-    if _postgres_password is None:
-        raise RuntimeError(
-            "POSTGRES_PASSWORD environment variable is not set. "
-            "This variable is required when DATABASE_TYPE=postgresql."
-        )
-    db = PooledPostgresqlDatabase(
-        os.environ.get("POSTGRES_DB", "sba_master"),
-        user=os.environ.get("POSTGRES_USER", "sba_admin"),
-        password=_postgres_password,
-        host=os.environ.get("POSTGRES_HOST", "sba_postgres"),
-        port=int(os.environ.get("POSTGRES_PORT", "5432")),
-        max_connections=20,
-        stale_timeout=300,  # 5 minutes
-        timeout=5,
-        autoconnect=False,
-        autorollback=True,  # Automatically rollback failed transactions
-    )
-else:
-    # Default SQLite configuration
-    db = SqliteDatabase(
-        "storage/sba_master.db",
-        pragmas={"journal_mode": "wal", "cache_size": -1 * 64000, "synchronous": 0},
     )
 
+db = PooledPostgresqlDatabase(
+    os.environ.get("POSTGRES_DB", "sba_master"),
+    user=os.environ.get("POSTGRES_USER", "sba_admin"),
+    password=_postgres_password,
+    host=os.environ.get("POSTGRES_HOST", "sba_postgres"),
+    port=int(os.environ.get("POSTGRES_PORT", "5432")),
+    max_connections=20,
+    stale_timeout=300,  # 5 minutes
+    timeout=5,
+    autoconnect=False,
+    autorollback=True,  # Automatically rollback failed transactions
+)
+
 date = f"{datetime.datetime.now().year}-{datetime.datetime.now().month}-{datetime.datetime.now().day}"
 logger = logging.getLogger("discord_app")