Add admin features, user profile management, and generation capabilities

- Implemented admin dashboard with user management features including role assignment and deletion.
- Added user profile page for updating email and password.
- Created separate routes and templates for text, image, and video generation with appropriate forms.
- Enhanced navigation with dropdown for generation options and loading overlay for better user experience.
- Introduced comprehensive error handling and user feedback through alerts.
- Updated styles for improved UI consistency and responsiveness.

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

frontend/app/templates/generate_image.html

@@ -0,0 +1,50 @@
+{% extends "base.html" %}
+{% block title %}Image Generation — AI Allucanget{% endblock %}
+{% block content %}
+<div class="card">
+  <h1>Image Generation</h1>
+  <form method="post">
+    <label for="model">Model</label>
+    <input id="model" name="model" type="text" required
+           placeholder="e.g. openai/dall-e-3"
+           value="{{ request.form.get('model', '') }}">
+
+    <label for="prompt">Prompt</label>
+    <textarea id="prompt" name="prompt" rows="4" required
+              placeholder="Describe the image you want…">{{ request.form.get('prompt', '') }}</textarea>
+
+    <label for="size">Size</label>
+    <select id="size" name="size">
+      <option value="1024x1024" {% if request.form.get('size','1024x1024')=='1024x1024' %}selected{% endif %}>1024×1024</option>
+      <option value="1792x1024" {% if request.form.get('size')=='1792x1024' %}selected{% endif %}>1792×1024 (landscape)</option>
+      <option value="1024x1792" {% if request.form.get('size')=='1024x1792' %}selected{% endif %}>1024×1792 (portrait)</option>
+      <option value="512x512"   {% if request.form.get('size')=='512x512' %}selected{% endif %}>512×512</option>
+    </select>
+
+    <label for="n">Number of images</label>
+    <select id="n" name="n">
+      <option value="1" {% if request.form.get('n','1')=='1' %}selected{% endif %}>1</option>
+      <option value="2" {% if request.form.get('n')=='2' %}selected{% endif %}>2</option>
+      <option value="4" {% if request.form.get('n')=='4' %}selected{% endif %}>4</option>
+    </select>
+
+    <button type="submit">Generate image</button>
+  </form>
+
+  {% if error %}
+    <div class="alert alert-error mt-2">{{ error }}</div>
+  {% endif %}
+
+  {% if result %}
+    <div class="result">
+      <h2>Generated image{{ 's' if result.images|length > 1 }}</h2>
+      {% for img in result.images %}
+        <img src="{{ img.url }}" alt="Generated image" class="generated-image">
+        {% if img.revised_prompt %}
+          <p class="text-muted mt-1" style="font-size:0.8rem;">{{ img.revised_prompt }}</p>
+        {% endif %}
+      {% endfor %}
+    </div>
+  {% endif %}
+</div>
+{% endblock %}