[fix] bandit sql warnings (#3242)

lnbits/core/crud/audit.py

@@ -30,10 +30,11 @@ async def delete_expired_audit_entries(
     conn: Optional[Connection] = None,
 ):
     await (conn or db).execute(
+        # Timestamp placeholder is safe from SQL injection (not user input)
         f"""
             DELETE from audit
             WHERE delete_at < {db.timestamp_now}
-        """,
+        """,  # noqa: S608
     )
 
 
@@ -48,13 +49,16 @@ async def get_count_stats(
         filters = Filters()
     clause = filters.where()
     data = await (conn or db).fetchall(
+        # SQL injection vectors safety:
+        # - `field` is a static string, not user input
+        # - `clause` is generated from filters, which are validated and sanitized
         query=f"""
             SELECT {field} as field, count({field}) as total
             FROM audit
             {clause}
             GROUP BY {field}
             ORDER BY {field}
-        """,
+        """,  # noqa: S608
         values=filters.values(),
         model=AuditCountStat,
     )
@@ -70,13 +74,15 @@ async def get_long_duration_stats(
         filters = Filters()
     clause = filters.where()
     long_duration_paths = await (conn or db).fetchall(
+        # This query is safe from SQL injection
+        # The `clause` is constructed from sanitized inputs
         query=f"""
             SELECT path as field, max(duration) as total FROM audit
             {clause}
             GROUP BY path
             ORDER BY total DESC
             LIMIT 5
-        """,
+        """,  # noqa: S608
         values=filters.values(),
         model=AuditCountStat,
     )