fix: update GitHub Pages stats and fix Docker ARM64 build

GitHub Pages Fixes:
- Updated search-index.json stats from 2057 to 4343 workflows
- Updated index.html title from "2000+" to "4300+" workflows
- Updated tagline to show "4343" workflows
- The JavaScript loads stats from search-index.json, not stats.json

Docker ARM64 Fix:
- Added gcc and python3-dev to Dockerfile
- Required for building psutil wheel on ARM64 architecture
- This fixes: "error: command 'gcc' failed: No such file or directory"

The GitHub Pages should now correctly display:
- Total Workflows: 4,343
- Active Workflows: 434
- Integrations: 268
- Categories: 16

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

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