Enforce strict citation format in summarizer prompt

- Added explicit examples of CORRECT vs WRONG citation formats
- Emphasized that citations must be EXACTLY [Doc X] with nothing else
- Updated system message to enforce strict formatting rules
- Added critical rules section to prevent LLM from being creative with citations

src/second_brain_online/application/agents/tools/summarizer.py

@@ -87,13 +87,19 @@ Create a two-part response:
    - DO NOT mention specific customer names or personal identifiers
    - Group related insights by topic with bullet points
    - Be concise and general, highlighting the problem/concern rather than individuals
-   - Add INLINE CITATIONS at the end of each point using format: [Doc X]
+   - Add INLINE CITATIONS at the end of each point using ONLY this format: [Doc X]
+   - CRITICAL: Citations must be EXACTLY "[Doc 1]", "[Doc 2]", etc. - nothing else
+   - DO NOT add any other information in citations (no titles, dates, IDs, or sources in the citation)
    - Number each unique document sequentially (Doc 1, Doc 2, etc.)
    
-   Example:
+   CORRECT Example:
    • Organizations are planning phone number porting transitions, but custom porting is expensive (~$1,000) and should be done in bulk [Doc 1]
    • Questions about additional license requirements for integrations ($45 per user) [Doc 1]
    • Ringtone volume issues in embedded Salesforce app [Doc 2]
+   
+   WRONG Example (DO NOT DO THIS):
+   • Custom porting costs around $1,000 [Source: JustCall Checkin, Document ID: abc123]
+   • License fees are $45 per user [JustCall, 2025-10-07]
 
 2. **📚 Sources** (at the end):
    - List ONLY UNIQUE documents (de-duplicate by Document ID)
@@ -131,7 +137,12 @@ Create a two-part response:
    - [Pricing Concern/High] Request for discount due to porting delays
    - [Policy Gap/Medium] No current policy for inactivity-based discounts
 
-Provide a focused answer with inline citations followed by the well-formatted Sources section with conversation insights."""
+Provide a focused answer with inline citations followed by the well-formatted Sources section with conversation insights.
+
+CRITICAL RULES:
+- In the ANSWER section, use ONLY [Doc X] format for citations
+- In the Sources section, provide full details about each Doc
+- NEVER mix citation formats - keep them separate and clean"""
 
     def __init__(self, *args, **kwargs) -> None:
         super().__init__(*args, **kwargs)
@@ -156,7 +167,7 @@ Provide a focused answer with inline citations followed by the well-formatted So
             messages=[
                 {
                     "role": "system",
-                    "content": "You are an expert analyst. Answer the user's question based on the search results provided. Create a comprehensive answer with a Sources section."
+                    "content": "You are an expert analyst. Follow the formatting instructions EXACTLY. Use only [Doc X] citations in the answer section, never include titles, dates, or IDs in citations."
                 },
                 {
                     "role": "user",