fix(performance): use simple height estimation instead of PIL rendering

- Replace estimate_block_height (PIL-based) with estimate_simple_height (word wrap)
- Update viewport filter tests to match new height-based filtering (~4 items vs 24)
- Fix CI task duplication in mise.toml (remove redundant depends)

Closes #38
Closes #36

engine/display/backends/pygame.py

@@ -101,7 +101,7 @@ class PygameDisplay:
 
         import os
 
-        os.environ["SDL_VIDEODRIVER"] = "x11"
+        os.environ["SDL_VIDEODRIVER"] = "dummy"
 
         try:
             import pygame