Start wxPython core scaffold with migration parity checklist

[Orinks]

Summary

• add a migration feature inventory + parity checklist with must-have vs later items
• add lean core scaffolding modules for settings persistence, logging bootstrap, and shortcut map
• wire startup/shutdown flow in AccessiClockApp around the new scaffolding
• update main entrypoint to support --portable and initialize file + console logging
• add focus-safe startup behavior in main window and log shortcut map
• add smoke tests for settings/logging/shortcut scaffolding

Test / Lint

• PYTHONPATH=src ruff check src tests ✅
• PYTHONPATH=src pytest -q tests/core tests/test_paths.py tests/test_constants.py ✅ (38 passed)
• PYTHONPATH=src pytest -q ⚠️ existing environment/dependency failures in audio tests (sound_lib, playsound3)

Migration notes

This keeps architecture intentionally simple for phase 1: small pure-python modules for persistence/logging/shortcuts and minimal app wiring.

Next phase plan

1. tighten dialog-level accessibility labels and keyboard flow
2. add GUI-level smoke test strategy on Windows runner
3. incrementally reduce direct _cache access behind tiny helpers
4. evaluate startup/pack-loading status announcements for screen reader clarity