style: apply ruff lint fixes and formatting to figment modules

Fixes: unused imports, import sorting, unused variable, overly broad
exception type in test.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

engine/scroll.py

@@ -18,8 +18,8 @@ from engine.frame import calculate_scroll_step
 from engine.layers import (
     apply_glitch,
     process_effects,
-    render_firehose,
     render_figment_overlay,
+    render_firehose,
     render_message_overlay,
     render_ticker_zone,
 )