Katana Stamina HUD Textures

Place two PNGs in this folder with exact filenames:
- katana_hud.png         -> colored version (will be filled vertically according to stamina)
- katana_hud_empty.png   -> grayscale/outline version (always shown behind)

Recommended canvas size: 96x256 px (portrait). You can change the expected size by editing:
  StaminaOverlay.KATANA_W and StaminaOverlay.KATANA_H

Rules:
- Both PNGs must share the same dimensions.
- The bottom of the image represents 0%-> filling starts from the bottom and grows upward.
- Transparent background is supported; only the katana pixels will be visible.

Positioning:
- The HUD draws at the right side of the screen, vertically centered.
- Adjust margin via StaminaOverlay.MARGIN_RIGHT.

If textures are missing, the overlay may not render the fill (you will still see numbers).