fix(dashboard): ensure repository root is in sys.path for app startup

[MichalRedm]

Summary

• Ensures that the STRIDE repository root directory is present in sys.path upon dashboard/app.py execution.
• Fixes ModuleNotFoundError: No module named 'dashboard' when launching the app via streamlit run .\dashboard\app.py.

Motivation

When invoking streamlit run .\dashboard\app.py, Streamlit's script runner bootstrap prepends the target script's parent directory (dashboard/) to sys.path[0]. Because modules across dashboard/ use package-level imports like from dashboard.components.sidebar import ..., Python fails to locate dashboard as a top-level package unless the project root is explicitly present on sys.path.

Key Changes

• In dashboard/app.py:
  • Resolved _PROJECT_ROOT = str(Path(__file__).resolve().parent.parent).
  • Added safe insertion sys.path.insert(0, _PROJECT_ROOT) before loading dashboard subcomponents.

Verification

• ruff check . passed with 0 errors
• ruff format --check . passed cleanly (105 files already formatted)
• python -m unittest discover tests passed with 22/22 tests passing and 0 failures
• Verified running streamlit run .\dashboard\app.py resolves package imports without error