chore: move generated blog HTML to site/blog/posts/, gitignore

- Generated HTML now in site/blog/posts/ (gitignored)
- CI workflow runs pandoc + make blog before deploy
- Updated all internal blog links to /blog/posts/ path
- blog/*.md remains the source of truth

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.github/workflows/static.yml

@@ -31,6 +31,10 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@v4
+      - name: Install pandoc
+        run: sudo apt-get install -y pandoc
+      - name: Generate blog HTML
+        run: make blog
       - name: Setup Pages
         uses: actions/configure-pages@v5
       - name: Upload artifact