# Health regeneration and starry sky

- Living players recover exactly one HP per elapsed gameplay second, including combat.
  Maximum is 100 HP; no healing or resurrection after death. Physics time accumulator
  handles frame-rate variation; time at full HP does not bank healing.
- `scripts/main.gd` uses a `PanoramaSkyMaterial` as the environment background.
  Ambient light remains the existing constant color; sky reflections are disabled.
- Compared local Half-Life skies `night`, `space`, and several `neb*` sets. `space`
  was selected for a plain star field (`night` is cloudy; nebulae are colorful).
- `assets/textures/sky/space_panorama.png`: 2048x1024 equirectangular conversion of
  the six Valve `space*.tga` faces, not a newly generated texture. The original faces
  are low resolution, so stars retain their original soft appearance. Source hashes
  are in `source_manifest.json`; original Steam files are never modified.

Reproduce (Pillow and FFmpeg with v360 required):

```sh
python3 tools/prepare_sky.py /path/to/Half-Life/valve/gfx/env
```

Verify with installed Godot 4.7.1:

```sh
"$G" --headless --path . --script res://tools/test_health_sky.gd
"$G" --display-driver x11 --rendering-method gl_compatibility --path . \
  --script res://tools/test_health_sky.gd -- --screenshot
```

Screenshot: `/tmp/zombie-star-window.png`. Test checks discrete timing, maximum,
no healing after death, panorama dimensions, and unchanged ambient light. Existing
music, grenade, wave, death, damage, and touch tests also pass. The existing resource
leak/in-use warnings at test shutdown remain; they are not fixed by this change.

Sky format reference: https://docs.godotengine.org/en/stable/classes/class_panoramaskymaterial.html