Tune english teacher to catch more errors, bump roast reply chance

- Raised sentence limit from 3 to 5 for english teacher mode
- Added instruction to list multiple corrections rapid-fire
- Roast mode reply chance: 10% -> 35%

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

config.yaml

@@ -76,7 +76,7 @@ modes:
     description: "Savage roast mode"
     prompt_file: "chat_roast.txt"
     proactive_replies: true
-    reply_chance: 0.10
+    reply_chance: 0.35
     moderation: relaxed
     relaxed_thresholds:
       warning_threshold: 0.85