Remove Jinja2 control structures from SPEC.yaml

Update the attempt counter example in SPEC.yaml to use substitution-only
template syntax instead of Jinja2 control structures ({% if %}).

The AI can naturally understand attempt context from {{current_attempt}},
{{max_attempts}}, and {{attempts_remaining}} variables without needing
conditional logic in the template itself.

This aligns with the substitution-only template system where logic lives
in scripts and templates only display pre-computed values.

research/SPEC.yaml

@@ -976,13 +976,12 @@ question: "Try {{current_attempt}}: What's your answer?"
 ai_feedback:
   tokens_for_ai: |
     This is attempt {{current_attempt}} of {{max_attempts}}.
-    {% if attempts_remaining == 1 %}
-      This is their last chance! Be clear and helpful.
-    {% elif attempts_remaining == 2 %}
-      They still have time. Provide a gentle hint.
-    {% else %}
-      Encourage them to think carefully.
-    {% endif %}
+    They have {{attempts_remaining}} attempts remaining.
+
+    Adjust your feedback based on the attempt number:
+    - On their last attempt: Be clear and helpful
+    - With 2 attempts left: Provide a gentle hint
+    - With more attempts: Encourage them to think carefully
 
 # Conditional content based on attempts:
 content_blocks: