Add Checkpoints feature with routes, template, and JavaScript integration

- Introduced CheckpointsRoutes for managing checkpoints-related endpoints and handling the checkpoints page.
- Added checkpoints.html template for rendering the checkpoints interface with a work-in-progress message.
- Implemented checkpoints.js to manage the initialization of the Checkpoints page and its components.
- Updated LoraManager to include checkpoints routes in the application setup, enhancing overall functionality.

templates/checkpoints.html

@@ -0,0 +1,27 @@
+{% extends "base.html" %}
+
+{% block title %}Checkpoints Manager{% endblock %}
+{% block page_id %}checkpoints{% endblock %}
+
+{% block preload %}
+<link rel="preload" href="/loras_static/js/checkpoints.js" as="script" crossorigin="anonymous">
+{% endblock %}
+
+{% block init_title %}Initializing Checkpoints Manager{% endblock %}
+{% block init_message %}Setting up checkpoints interface. This may take a few moments...{% endblock %}
+{% block init_check_url %}/api/checkpoints?page=1&page_size=1{% endblock %}
+
+{% block content %}
+<div class="work-in-progress">
+    <div class="wip-content">
+        <i class="fas fa-tools"></i>
+        <h2>Checkpoints Manager</h2>
+        <p>This feature is currently under development and will be available soon.</p>
+        <p>Please check back later for updates!</p>
+    </div>
+</div>
+{% endblock %}
+
+{% block main_script %}
+<script type="module" src="/loras_static/js/checkpoints.js"></script>
+{% endblock %}