v0.3.0: game-window picker + NCC recognition + artifacts + ?-merged

- window_capture.py: enumerate top-level windows (pygetwindow) and
  capture a specific one via PrintWindow PW_RENDERFULLCONTENT (works
  on non-focused windows). Linux falls back to mss region grab.
- recognizer.py: replace MAE matcher with NCC over numpy vectors.
  Each rotatable slab generates 4 templates (0/90/180/270). Adds 248
  artifact templates and an empty-cell heuristic (low mean/std-dev).
  Cells below confidence floor are tagged "unknown" — likely merged
  "?" boxes.
- gui.py: new ScreenshotFrame with [게임 창 선택] button → window
  picker dialog → bbox crop → recognize → editable preview grid with
  per-cell CellEditor that handles slab / artifact / merged(?) / empty.
  Merged cells let user pick which two slabs got combined + a level.
- artifacts.py + bundled _artifacts.json (248 entries from
  WhiteDog1004/sephiria) for matching and rendering.
- renderer.py: factored CDN fetch into _fetch_image; added
  fetch_artifact_image().
- requirements.txt: + numpy, pygetwindow (Win), pywin32 (Win).
- docker-build-cmd.sh: upgrade PyInstaller to 5.x inside cdrx
  container so numpy DLL manifest reads work.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

requirements.txt

@@ -1,3 +1,6 @@
 Pillow>=9.0
 requests>=2.25
 mss>=6.0
+numpy>=1.21,<2.0
+pygetwindow>=0.0.9 ; sys_platform == "win32"
+pywin32>=305 ; sys_platform == "win32"