fix(core): remove zero-findings halt condition from edge case hunter (#1797)

The "HALT if zero findings" condition pressures the LLM to hallucinate
findings when reviewing trivial diffs with no branching logic. Since
this task runs non-interactively as a subagent, it cannot ask for
guidance either. Zero findings is a valid outcome for clean code.

src/core/tasks/review-edge-case-hunter.xml

@@ -57,7 +57,6 @@ No extra text, no explanations, no markdown wrapping.</output-format>
   </flow>
 
   <halt-conditions>
-    <condition>HALT if zero findings - this is suspicious, re-analyze or ask for guidance</condition>
     <condition>HALT if content is empty or unreadable</condition>
   </halt-conditions>