Add interactive slide decks for two SIGGRAPH papers

Add HTML presentations under slides/conformal/ and slides/seamless/
with KaTeX math, scroll-wheel paging, and embedded figures.
Link to them from the publications section in index.html.

Author: zlyfunction

index.html

@@ -884,6 +884,7 @@ <h2 class="section-title" data-en="Selected Publications" data-zh="代表性论
                             target="_blank" data-en="Paper" data-zh="论文">Paper</a>
                         <a class="pub-btn" href="https://github.com/hankstag/seamless_signature"
                             target="_blank" data-en="Code" data-zh="代码">Code</a>
+                        <a class="pub-btn" href="./slides/seamless/" target="_blank" data-en="Slides" data-zh="幻灯片">Slides</a>
                         <button class="pub-btn" onclick="toggleAbstract('abstract1')" data-en="Abstract" data-zh="摘要">Abstract</button>
                     </div>
                     <div id="abstract1" class="abstract">
@@ -921,6 +922,7 @@ <h2 class="section-title" data-en="Selected Publications" data-zh="代表性论
                             target="_blank" data-en="Paper" data-zh="论文">Paper</a>
                         <a class="pub-btn" href="https://github.com/geometryprocessing/ConformalIdealDelaunay"
                             target="_blank" data-en="Code" data-zh="代码">Code</a>
+                        <a class="pub-btn" href="./slides/conformal/" target="_blank" data-en="Slides" data-zh="幻灯片">Slides</a>
                         <button class="pub-btn" onclick="toggleAbstract('abstract2')" data-en="Abstract" data-zh="摘要">Abstract</button>
                     </div>
                     <div id="abstract2" class="abstract">