Add formatting guidelines to weekly-issue-summary workflow

.github/workflows/weekly-issue-summary.md

@@ -140,15 +140,66 @@ If insufficient data is available (less than 7 days):
 
 ---
 
+## 📝 Report Formatting Guidelines
+
+**CRITICAL**: Follow these formatting guidelines to create well-structured, readable reports:
+
+### 1. Header Levels
+**Use h3 (###) or lower for all headers in your report to maintain proper document hierarchy.**
+
+The discussion title serves as h1, so all content headers should start at h3:
+- Use `###` for main sections (e.g., "### Weekly Overview", "### Key Trends")
+- Use `####` for subsections (e.g., "#### Issue Breakdown by Label")
+- Never use `##` (h2) or `#` (h1) in the report body
+
+### 2. Progressive Disclosure
+**Wrap long sections in `<details><summary><b>Section Name</b></summary>` tags to improve readability and reduce scrolling.**
+
+Use collapsible sections for:
+- Full issue lists with titles and descriptions
+- Detailed breakdowns by label or type
+- Historical comparisons or verbose data
+
+Example:
+```markdown
+<details>
+<summary><b>Full Issue List</b></summary>
+
+[Long list of issues...]
+
+</details>
+```
+
+### 3. Report Structure Pattern
+
+Your report should follow this structure for optimal readability:
+
+1. **Weekly Overview** (always visible): 1-2 paragraph summary of the week's issue activity, highlighting key trends
+2. **Key Trends** (always visible): Notable patterns like increased activity, common issue types, or emerging topics
+3. **Summary Statistics** (always visible): Total counts, comparisons to previous week, breakdown by state/label
+4. **Detailed Issue Breakdown** (in `<details>` tags): Complete list of issues with titles, numbers, authors, and labels
+5. **Recommendations for Upcoming Week** (always visible): Actionable suggestions based on the analysis
+
+### Design Principles
+
+Create reports that:
+- **Build trust through clarity**: Most important info (overview, trends, key stats) immediately visible
+- **Exceed expectations**: Add helpful context, week-over-week comparisons, trend analysis
+- **Create delight**: Use progressive disclosure to reduce overwhelm for detailed data
+- **Maintain consistency**: Follow the same patterns as other reporting workflows
+
+---
+
 ## Weekly Analysis
 
 Analyze all issues opened in the repository ${{ github.repository }} over the last 7 days.
 
-**Report Structure**: Use h3 (###) or lower for all headers in your summary report.
-
 Create a comprehensive summary that includes:
 - Total number of issues opened
 - List of issue titles with their numbers and authors
 - Any notable patterns or trends (common labels, types of issues, etc.)
 
-Format the summary clearly with proper markdown formatting for easy reading.
+Follow the **Report Formatting Guidelines** above to structure your report with:
+- h3 (###) for main section headers
+- Detailed issue lists wrapped in `<details>` tags
+- Critical information (overview, trends, statistics, recommendations) always visible