fix: resolve CI/CD configuration issues

- Fix linting path from envschema/ to src/
- Fix package verification from envschema to memory_manager
- Add proper build-system and package-dir to pyproject.toml
- Add missing import os in tui/app.py

src/memory_manager/tui/app.py

@@ -1,3 +1,5 @@
+"""Textual TUI application for the memory manager."""
+
 import os
 from datetime import datetime
 from typing import Any