Add models caching and management functionality with corresponding API endpoints and templates

Co-authored-by: Copilot <copilot@github.com>

frontend/app/templates/generate_video.html

@@ -19,6 +19,13 @@ AI{% endblock %} {% block content %}
         <input type="hidden" name="mode" value="text" />
 
         <label for="model-t">Model</label>
+        {% if models %}
+        <select id="model-t" name="model" required>
+          {% for m in models %}
+          <option value="{{ m.id }}" {% if request.form.get('model', '') == m.id and request.form.get('mode','text')=='text' %}selected{% endif %}>{{ m.name }}</option>
+          {% endfor %}
+        </select>
+        {% else %}
         <input
           id="model-t"
           name="model"
@@ -27,6 +34,7 @@ AI{% endblock %} {% block content %}
           placeholder="e.g. openai/sora-2-pro"
           value="{{ request.form.get('model', '') if request.form.get('mode','text')=='text' else '' }}"
         />
+        {% endif %}
 
         <label for="prompt-t">Prompt</label>
         <textarea
@@ -80,6 +88,13 @@ AI{% endblock %} {% block content %}
         <input type="hidden" name="mode" value="image" />
 
         <label for="model-i">Model</label>
+        {% if models %}
+        <select id="model-i" name="model" required>
+          {% for m in models %}
+          <option value="{{ m.id }}" {% if request.form.get('model', '') == m.id and request.form.get('mode')=='image' %}selected{% endif %}>{{ m.name }}</option>
+          {% endfor %}
+        </select>
+        {% else %}
         <input
           id="model-i"
           name="model"
@@ -88,6 +103,7 @@ AI{% endblock %} {% block content %}
           placeholder="e.g. openai/sora-2-pro"
           value="{{ request.form.get('model', '') if request.form.get('mode')=='image' else '' }}"
         />
+        {% endif %}
 
         <label for="image_url">Source image URL</label>
         <input