feat: intégration plugin Kirby SEO

- Ajout de tobimori/kirby-seo via Composer
- snippet('seo/head') dans header.php (remplace les meta manuels)
- snippet('seo/schemas') dans footer.php pour JSON-LD
- Onglet SEO ajouté dans site.yml et tous les blueprints de pages
- Configuration SEO dans config.php (sitemap, robots, canonicalBase TODO)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

site/plugins/kirby-seo/docs/2_customization/02_robots-txt.md

@@ -0,0 +1,66 @@
+---
+title: Customizing robots.txt
+intro: Add custom rules to your robots.txt
+---
+
+By default, Kirby SEO generates a simple `robots.txt` that allows all crawlers and blocks the Panel. If you need to add your own rules, use the `robots.content` option.
+
+## Blocking specific bots
+
+Some AI providers crawl websites to use the content as training data. You can block their crawlers:
+
+```php
+<?php
+// site/config/config.php
+
+return [
+  'tobimori.seo' => [
+    'robots' => [
+      'content' => [
+        'GPTBot' => [
+          'Disallow' => ['/'],
+        ],
+        'Google-Extended' => [
+          'Disallow' => ['/'],
+        ],
+        'CCBot' => [
+          'Disallow' => ['/'],
+        ],
+      ],
+    ],
+  ],
+];
+```
+
+This adds rules for each bot while keeping the default rules for all other crawlers intact.
+
+## Custom rules for all crawlers
+
+If you set rules for `*`, they replace the default rules entirely:
+
+```php
+'content' => [
+  '*' => [
+    'Allow' => ['/'],
+    'Disallow' => ['/panel', '/content', '/private'],
+  ],
+],
+```
+
+## Mixing rules
+
+You can combine rules for all crawlers with rules for specific bots:
+
+```php
+'content' => [
+  '*' => [
+    'Allow' => ['/'],
+    'Disallow' => ['/panel', '/content'],
+  ],
+  'GPTBot' => [
+    'Disallow' => ['/'],
+  ],
+],
+```
+
+The `Sitemap:` line is added automatically if the [sitemap module](1_features/01_sitemap) is active. You can override it with the `robots.sitemap` option.