chore: remove entire src/snek/docs directory with app, templates, and static assets

This commit deletes the documentation subsystem including the aiohttp-based Application class, all Jinja2/Markdown templates (base.html, index.html, api.html, form_api_python.html, form_api_javascript.html), and associated CSS styling. The removal eliminates the MarkdownExtension integration, the catch-all route handler for document serving, and all rendered documentation pages from the repository.

src/snekbak/templates/message.html

@@ -0,0 +1,10 @@
+<style>
+    {{highlight_styles}}
+</style>
+{#
+    <div data-uid="{{uid}}" data-color="{{color}}" data-channel_uid="{{channel_uid}}" data-user_nick="{{user_nick}}" data-created_at="{{created_at}}" data-user_uid="{{user_uid}}" data-message="{{message}}" class="message"><div class="avatar" style="background-color: {{color}}; color: black;">{{user_nick[0]}}</div><div class="message-content"><div class="author" style="color: {{color}};">{{user_nick}}</div><div class="text">
+#}
+        {% markdown %}{% autoescape false %}{{ message }}{%endautoescape%}{% endmarkdown %}
+{#}
+    </div><div class="time">{{created_at}}</div></div></div>
+{#}