feat(ai): handle temperature incompatibility for gpt-5 and o-series models, add model picker UI

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

frontend/templates/settings.html

@@ -139,6 +139,29 @@
                   Enable {{ setting.key.replace('_', ' ').title() }}
                 </label>
               </div>
+              {% elif setting.metadata.type == 'model_picker' %}
+              <!-- Model Picker: free-text input with datalist of common models -->
+              <div class="relative">
+                <input
+                  type="text"
+                  id="{{ setting.key }}"
+                  name="{{ setting.key }}"
+                  list="{{ setting.key }}_models"
+                  x-model="formData['{{ setting.key }}']"
+                  class="setting-input w-full px-3 py-2 border border-gray-300 rounded-md shadow-sm focus:outline-none focus:ring-blue-500 focus:border-blue-500"
+                  placeholder="Select a common model or type a custom name…"
+                  autocomplete="off"
+                />
+                <datalist id="{{ setting.key }}_models">
+                  {% for m in setting.metadata.suggested_models %}
+                  <option value="{{ m }}">{{ m }}</option>
+                  {% endfor %}
+                </datalist>
+                <p class="text-xs text-gray-400 mt-1">
+                  <i class="fas fa-info-circle mr-1"></i>
+                  Pick from the list or type any model name supported by your provider.
+                </p>
+              </div>
               {% elif setting.metadata.options %}
               <!-- Dropdown Select for fields with a fixed list of values -->
               <select