refactor(reports): remove column headers from summary table

Remove 'Metric' and 'Value' headers from summary table as the bold
labels in each row make it self-explanatory. Cleaner, more scannable
presentation.

Assisted-by: Claude Sonnet 4.5 via GitHub Copilot

Author: castrojo

reports/2026-01-31-report.mdx

@@ -10,7 +10,7 @@ import GitHubProfileCard from '@site/src/components/GitHubProfileCard';
 
 # Summary
 
-| Metric | Value |
+| | |
 |--------|-------|
 | **Total Items** | 144 (36 planned, 108 opportunistic) |
 | **Contributors** | 23 total, 10 new |

scripts/lib/markdown-generator.mjs

@@ -116,7 +116,7 @@ import GitHubProfileCard from '@site/src/components/GitHubProfileCard';
   // Generate summary section as compact table
   const summary = `# Summary
 
-| Metric | Value |
+| | |
 |--------|-------|
 | **Total Items** | ${totalItems} (${plannedItems.length} planned, ${opportunisticItems.length} opportunistic) |
 | **Contributors** | ${contributors.length} total, ${newContributors.length} new |