feat: add Jinja2 server-side rendering with template components and locust load testing

Introduce a full server-side rendering pipeline using Jinja2Templates, including base layout, navigation, modals, and rant card components. Add a classic.html static fallback page and a locustfile.py for load testing the new endpoints. Update main.py to mount static files, create template directories on startup, and add a format_time helper for relative timestamps.

templates/feed.html

@@ -0,0 +1,16 @@
+{% extends 'base.html' %}
+{% from 'components/rant_card.html' import render_rant_card %}
+
+{% block content %}
+<div class="sort-options">
+    <a href="/?sort=recent" class="sort-btn {% if current_sort == 'recent' %}active{% endif %}">Recent</a>
+    <a href="/?sort=top" class="sort-btn {% if current_sort == 'top' %}active{% endif %}">Top</a>
+    <a href="/?sort=algo" class="sort-btn {% if current_sort == 'algo' %}active{% endif %}">Algorithm</a>
+</div>
+
+<div>
+    {% for rant in rants %}
+        {{ render_rant_card(rant) }}
+    {% endfor %}
+</div>
+{% endblock %}