style: apply ruff auto-fixes across codebase

- Fix import sorting (isort) across all engine modules
- Fix SIM105 try-except-pass patterns (contextlib.suppress)
- Fix nested with statements in tests
- Fix unused loop variables

Run 'uv run pytest' to verify tests still pass.

engine/scroll.py

@@ -3,16 +3,23 @@ Render engine — ticker content, scroll motion, message panel, and firehose ove
 Depends on: config, terminal, render, effects, ntfy, mic.
 """
 
+import random
 import re
 import sys
 import time
-import random
 from datetime import datetime
 
 from engine import config
-from engine.terminal import RST, W_COOL, CLR, tw, th
+from engine.effects import (
+    fade_line,
+    firehose_line,
+    glitch_bar,
+    next_headline,
+    noise,
+    vis_trunc,
+)
 from engine.render import big_wrap, lr_gradient, lr_gradient_opposite, make_block
-from engine.effects import noise, glitch_bar, fade_line, vis_trunc, next_headline, firehose_line
+from engine.terminal import CLR, RST, W_COOL, th, tw
 
 
 def stream(items, ntfy_poller, mic_monitor):