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/classes/Ai/Driver.php

@@ -0,0 +1,40 @@
+<?php
+
+namespace tobimori\Seo\Ai;
+
+use Generator;
+use Kirby\Exception\InvalidArgumentException;
+use tobimori\Seo\Seo;
+
+abstract class Driver
+{
+	public function __construct(protected string $providerId)
+	{
+	}
+
+	/**
+	 * Streams a response for the given content.
+	 *
+	 * @param array<Content> $content Array of Content messages forming a conversation.
+	 * @param string|null $model Model override.
+	 *
+	 * @return Generator<int, Chunk, mixed, void>
+	 */
+	abstract public function stream(array $content, string|null $model = null): Generator;
+
+	/**
+	 * Returns a configuration value or throws when required.
+	 */
+	protected function config(string $key, mixed $default = null, bool $required = false): mixed
+	{
+		$value = Seo::option("ai.providers.{$this->providerId}.config.{$key}", $default);
+
+		if ($required === true && ($value === null || $value === '')) {
+			throw new InvalidArgumentException(
+				"Missing required \"{$key}\" configuration for driver " . static::class . '.'
+			);
+		}
+
+		return $value;
+	}
+}