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/Drivers/Gemini.php

@@ -0,0 +1,149 @@
+<?php
+
+namespace tobimori\Seo\Ai\Drivers;
+
+use Generator;
+use tobimori\Seo\Ai\Chunk;
+use tobimori\Seo\Ai\Content;
+use tobimori\Seo\Ai\Driver;
+use tobimori\Seo\Ai\SseStream;
+
+class Gemini extends Driver
+{
+	protected const string DEFAULT_ENDPOINT = 'https://generativelanguage.googleapis.com/v1beta';
+	protected const string DEFAULT_MODEL = 'gemini-3.1-flash-lite-preview';
+
+	/**
+	 * @inheritDoc
+	 */
+	public function stream(
+		array $content,
+		string|null $model = null,
+	): Generator {
+		$apiKey = $this->config('apiKey', required: true);
+		$model = $model ?? $this->config('model', static::DEFAULT_MODEL);
+		$baseEndpoint = $this->config('endpoint', static::DEFAULT_ENDPOINT);
+		$endpoint = "{$baseEndpoint}/models/{$model}:streamGenerateContent?alt=sse&key={$apiKey}";
+
+		$headers = [
+			'Content-Type: application/json',
+		];
+
+		$payload = [
+			'contents' => $this->buildContents($content),
+		];
+
+		$systemInstruction = $this->buildSystemInstruction($content);
+		if ($systemInstruction !== null) {
+			$payload['systemInstruction'] = $systemInstruction;
+		}
+
+		$stream = new SseStream($endpoint, $headers, $payload, (int)$this->config('timeout', 120));
+		$started = false;
+
+		yield from $stream->stream(function (array $event) use (&$started): Generator {
+			$candidates = $event['candidates'] ?? [];
+			$candidate = $candidates[0] ?? null;
+
+			if ($candidate === null) {
+				$error = $event['error'] ?? null;
+				if ($error) {
+					yield Chunk::error($error['message'] ?? 'Unknown Gemini error.', $event);
+				}
+				return;
+			}
+
+			if (!$started) {
+				yield Chunk::streamStart($event);
+				yield Chunk::textStart($event);
+				$started = true;
+			}
+
+			$finishReason = $candidate['finishReason'] ?? null;
+			if ($finishReason === 'SAFETY') {
+				yield Chunk::error('Response blocked by safety filters.', $event);
+				return;
+			}
+
+			$parts = $candidate['content']['parts'] ?? [];
+			foreach ($parts as $part) {
+				$text = $part['text'] ?? '';
+				if ($text !== '') {
+					yield Chunk::textDelta($text, $event);
+				}
+			}
+
+			if ($finishReason !== null) {
+				yield Chunk::textComplete($event);
+				yield Chunk::streamEnd($event);
+			}
+		});
+	}
+
+	/**
+	 * Translates an array of Content messages into the Gemini contents format.
+	 *
+	 * @param array<Content> $content
+	 */
+	private function buildContents(array $content): array
+	{
+		$contents = [];
+
+		foreach ($content as $message) {
+			if ($message->role() === 'system') {
+				continue;
+			}
+
+			$parts = [];
+			foreach ($message->blocks() as $block) {
+				if ($block['type'] === 'image') {
+					$parts[] = [
+						'inline_data' => [
+							'mime_type' => $block['mediaType'],
+							'data' => $block['data'],
+						],
+					];
+				} elseif ($block['type'] === 'text') {
+					$parts[] = [
+						'text' => $block['text'],
+					];
+				}
+			}
+
+			$contents[] = [
+				'role' => $message->role() === 'assistant' ? 'model' : 'user',
+				'parts' => $parts,
+			];
+		}
+
+		return $contents;
+	}
+
+	/**
+	 * Extracts system messages into a Gemini systemInstruction object.
+	 *
+	 * @param array<Content> $content
+	 */
+	private function buildSystemInstruction(array $content): array|null
+	{
+		$parts = [];
+
+		foreach ($content as $message) {
+			if ($message->role() !== 'system') {
+				continue;
+			}
+
+			foreach ($message->blocks() as $block) {
+				if ($block['type'] === 'text') {
+					$parts[] = ['text' => $block['text']];
+				}
+			}
+		}
+
+		if ($parts === []) {
+			return null;
+		}
+
+		return ['parts' => $parts];
+	}
+}