feat: enhance batch report with interactive features and visual improvements

Implemented Phase 2 enhancements from .plans/batch-report-enhancements.md:

- Added certification tier descriptions (2-3 sentences per tier)
- Repositioned repository table below certification section with intro text
- Added interactive table sorting (click headers to sort columns)
- Added table filtering (search box filters by repo, cert, language)
- Implemented seaborn-style heatmap for top 10 failing attributes
- Converted language/attribute sections to responsive 2-column layout

Technical changes:
- Updated CSP to allow inline scripts for interactivity
- Added JavaScript for table sorting with data-value attributes
- Added responsive CSS Grid layout (stacks on mobile <1024px)
- Implemented color-coded heatmap with hover tooltips
- Initial sort by score (descending) on page load

All changes are template-only (no Python modifications needed).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: jeremyeder