feat: v2.6.0 3-step AI pipeline, VPS worker, REST worker routes

- 3-step OpenRouter pipeline: Gatekeeper scoring/classification, PubMed+Google URL extraction, Markdown summary generation
- REST worker routes /wp-json/peptide-news/v1/worker/* with X-Peptide-News-Token auth
- Standalone Coolify worker (tools/vps-worker) with Dockerfile + docker-compose
- CLI commands, content extractor, pubmed extractor, google url resolver
- 89 PHPUnit tests passing

tools/vps-worker/Dockerfile

@@ -0,0 +1,11 @@
+FROM php:8.3-cli-alpine
+
+# Install curl extension and ca-certificates for secure HTTPS requests
+RUN apk add --no-cache curl ca-certificates && \
+    docker-php-ext-install curl || true
+
+WORKDIR /app
+COPY worker.php /app/worker.php
+
+# Default entrypoint runs the worker
+CMD ["php", "/app/worker.php"]