use actual em-dashes in checklist examples

prompts/LLM_PROSE_TELLS.md

@@ -307,9 +307,9 @@ introduces another.
 
 ### Pass 2: Sentence-Level Restructuring
 
-10. Find every em-dash pivot ("not X...but Y," "not just X...Y," "more than
+10. Find every em-dash pivot ("not X—but Y," "not just X—Y," "more than X—Y")
-    X...Y") and rewrite it as two separate clauses or a single sentence that
+    and rewrite it as two separate clauses or a single sentence that makes the
-    makes the point without the negation-then-correction structure.
+    point without the negation-then-correction structure.
 
 11. Find every colon elaboration and check whether it's doing real work. If the
     clause before the colon could be deleted without losing meaning, rewrite the