chore: fix linting issues in plugins after refactor

- Remove unused imports in glitch.py
- Remove unused variables in hud.py

engine/effects/plugins/glitch.py

@@ -1,8 +1,7 @@
 import random
 
-from engine import config
 from engine.effects.types import EffectConfig, EffectContext, EffectPlugin
-from engine.terminal import C_DIM, DIM, G_DIM, G_LO, RST
+from engine.terminal import DIM, G_LO, RST
 
 
 class GlitchEffect(EffectPlugin):
@@ -29,7 +28,7 @@ class GlitchEffect(EffectPlugin):
             original_lengths = [len(ansi_pattern.sub("", line)) for line in result]
             for _ in range(min(n_hits, len(result))):
                 gi = random.randint(0, len(result) - 1)
-                original_line = result[gi]
+                result[gi]
                 target_len = original_lengths[gi]  # Use stored original length
                 glitch_bar = self._glitch_bar(target_len)
                 result[gi] = glitch_bar