feat: add bus photos and repo links to blog

The blog needed a visual identity and a path back to the source:
hero photo of the Axer on the home page, village photo and repo link
on the about page, and a git-clone nav link.

Privacy pass before the repo goes public: move the two cab photos
with an identifiable face and the seller ad screenshot out of the
repo (kept in BUS-photos-privees locally), update INDEX.md and
CLAUDE.md accordingly.

blog/themes/terminal-bus/layouts/baseof.html

@@ -20,6 +20,7 @@
     <span class="prompt">{{ site.Params.prompt }}:~$</span>
     <a href="{{ "/" | relURL }}">ls posts/</a>
     <a href="{{ "/a-propos/" | relURL }}">cat a-propos.md</a>
+    <a href="https://git.saillant.cc/electron-rare/bus-axer">git clone</a>
   </nav>
 </header>
 <main>