feat: add alt text extraction from URLs for images and improve CSS variable usage for progress bars

Add `_alt_from_url` helper in Python rendering and `altFromUrl` in JS ContentRenderer to generate descriptive alt attributes from image filenames, replacing empty alt strings. Update image embed templates and Avatar component to use derived alt text. Migrate inline `style.width` assignments to CSS custom properties (`--poll-pct`, `--hud-xp`, `--quest-pct`, `--bar-pct`, `--quota-pct`) across PollManager, GameFarm, and profile/quest CSS for better maintainability. Introduce new admin, docs, projects, services, and base CSS utility classes. Add "Code Farm" docs page entry.

devplacepy/templates/_poll.html

@@ -4,7 +4,7 @@
     <div class="poll-options" role="group" aria-label="Poll options">
         {% for opt in _poll.options %}
         <button type="button" class="poll-option{% if _poll.my_choice == opt.uid %} chosen{% endif %}" data-option-uid="{{ opt.uid }}" aria-pressed="{% if _poll.my_choice == opt.uid %}true{% else %}false{% endif %}"{{ guest_disabled(user) }}>
-            <span class="poll-option-bar" style="width: {{ opt.pct }}%;"></span>
+            <span class="poll-option-bar" style="--poll-pct: {{ opt.pct }}%;"></span>
             <span class="poll-option-label">{{ render_title(opt.label) }}</span>
             <span class="poll-option-meta">
                 <span class="poll-option-check" aria-hidden="true"{% if _poll.my_choice != opt.uid %} hidden{% endif %}>&#x2713;</span>