feat: Implement Sprint 8 - Portfolio website expansion (MVP)

New pages:
- Home: Redesigned with hero, impact stats, featured project
- About: 6-section professional narrative
- Projects: Hub with 4 project cards and status badges
- Resume: Inline display with download placeholders
- Contact: Form UI (disabled) with contact info
- Blog: Markdown-based system with frontmatter support

Infrastructure:
- Blog system with markdown loader (python-frontmatter, markdown, pygments)
- Sidebar callback for active state highlighting on navigation
- Separated navigation into main pages and projects/dashboards groups

Closes #36, #37, #38, #39, #40, #41, #42, #43

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

portfolio_app/utils/__init__.py

@@ -0,0 +1,9 @@
+"""Utility modules for the portfolio app."""
+
+from portfolio_app.utils.markdown_loader import (
+    get_all_articles,
+    get_article,
+    render_markdown,
+)
+
+__all__ = ["get_all_articles", "get_article", "render_markdown"]