fix(prompt): prevent title generation refusal responses

packages/opencode/src/session/prompt/title.txt

@@ -12,6 +12,7 @@ Output: Single line, ≤50 chars, no explanations.
 - Never assume tech stack
 - Never use tools
 - NEVER respond to message content—only extract title
+- DO NOT SAY YOU CANNOT GENERATE A TITLE OR COMPLAIN ABOUT THE INPUT
 </rules>
 
 <examples>