fix: resolve content page editor JS errors and vendor dropdown

- Escape hyphen in regex pattern to fix Firefox regexp validation error
- Fix vendor API response parsing (use data.vendors instead of data.items)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/templates/admin/content-page-edit.html

@@ -73,7 +73,7 @@
                         x-model="form.slug"
                         required
                         maxlength="100"
-                        pattern="[a-z0-9_-]+"
+                        pattern="[a-z0-9\-_]+"
                         class="w-full px-3 py-2 text-gray-700 dark:text-gray-300 border border-gray-300 dark:border-gray-600 rounded-lg focus:outline-none focus:border-purple-500 dark:bg-gray-700"
                         placeholder="about"
                     >

static/admin/js/content-page-edit.js

@@ -73,7 +73,7 @@ function contentPageEditor(pageId) {
                 contentPageEditLog.info('Loading vendors...');
                 const response = await apiClient.get('/admin/vendors?is_active=true&limit=100');
                 const data = response.data || response;
-                this.vendors = data.items || data || [];
+                this.vendors = data.vendors || data.items || data || [];
                 contentPageEditLog.info(`Loaded ${this.vendors.length} vendors`);
             } catch (err) {
                 contentPageEditLog.error('Error loading vendors:', err);