docs: clarify references formatting in summary prompt

- Add explicit instruction that each reference should be on a separate line
- Update output template to show line breaks between references
- Make reference formatting requirements more explicit for LLM

Author: dividor

src/pia_mcp_server/prompts/handlers.py

@@ -110,6 +110,7 @@ def _generate_summary_prompt(arguments: Dict[str, str]) -> str:
 
 3. **References section format:**
    - Numbered list matching the inline citations.
+   - **Each reference on a separate line**.
    - Each reference must include:
      - **Document title**
      - **Page number** (or "n/a" if page not given in source)
@@ -140,6 +141,7 @@ def _generate_summary_prompt(arguments: Dict[str, str]) -> str:
 References:
 [1] Document Title — Page X — Source Name — URL
 [2] Document Title — Page X — Source Name — URL
+[3] Document Title — Page X — Source Name — URL
 ...
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