docs(sidebar): Add libtmux-mcp and pytest links to tmux-python group

why: Sidebar projects list was copied from libtmux and didn't include
libtmux-mcp. Also restructure tmux-python to match cihai's multi-line
layout for better readability.
what:
- Switch tmux-python to indented layout (like cihai group)
- Add mcp and pytest sub-links under libtmux

Author: tony

docs/_templates/sidebar/projects.html

@@ -13,8 +13,14 @@
   </p>
   <p class="indented-block">
     <span class="project-name">tmux-python</span>
-    <a class="internal" href="https://tmuxp.git-pull.com">tmuxp</a>
-    (<a class="internal" href="https://libtmux.git-pull.com">libtmux</a>)
+    <span class="indent">
+      <a class="internal" href="https://tmuxp.git-pull.com">tmuxp</a>
+    </span>
+    <span class="indent">
+      <a class="internal" href="https://libtmux.git-pull.com">libtmux</a>
+      (<a class="internal" href="https://libtmux-mcp.git-pull.com">mcp</a>,
+      <a class="internal" href="https://libtmux.git-pull.com/pytest-plugin/">pytest</a>)
+    </span>
   </p>
 
   <p class="indented-block">