Create a VkPipelineCache at device init, loaded from disk if available.
All 65 pipeline creation calls across 19 renderer files now use the
shared cache. On shutdown, the cache is serialized to disk so subsequent
launches skip redundant shader compilation.
Cache path: ~/.local/share/wowee/pipeline_cache.bin (Linux),
~/Library/Caches/wowee/ (macOS), %APPDATA%\wowee\ (Windows).
Stale/corrupt caches are handled gracefully (fallback to empty cache).
Fixes issue where dust particles were angling down into terrain and not visible.
Changes spawn position to fixed 0.2 units above ground, increases upward velocity
to 1.2-2.5 for clearer rise, and uses only horizontal velocity component for drift
to prevent Z component from pushing particles downward.
Implemented dust cloud particles that spawn at mount feet when running
on the ground, similar to the original WoW. Features:
- Brownish/tan dust particles using point sprite rendering
- Spawn rate proportional to movement speed
- Particles rise up, drift backward, and fade out naturally
- Only active when mounted, moving, and on ground (not flying)
- Smooth particle animation with size growth and alpha fade
Uses similar particle system architecture as swim effects with
GL_POINTS rendering and custom shaders for soft circular particles.
