Refactor database management and schema initialization

- Removed the old npc_memory.db file.
- Updated time.txt with a new timestamp.
- Refactored transaction recording in bank_functions.py to use parameterized queries.
- Enhanced DatabaseManager in sql_commands.py to support singleton pattern and improved table creation logic.
- Added methods for sanitizing SQL identifiers and parsing insert columns for upsert operations.
- Improved error handling and connection management in execute_query, fetch_one, fetch_all, and fetch_as_dataframe methods.
- Introduced a new bootstrap_database.py script for initializing the database schema.
- Updated app.py to use the new initialize_database function for database management.

cogs/customCommands.py

@@ -63,7 +63,7 @@ class CustomCommandsCog(commands.Cog):
             )
             self.invalidate_cache(guild_id)  # Invalidate cache after change
 
-            if deleted_rows is not None and len(deleted_rows) > 0:
+            if deleted_rows and deleted_rows > 0:
                 await ctx.send(f"Custom command `{command_name}` has been deleted!")
             else:
                 await ctx.send(f"Custom command `{command_name}` not found.")