feat(seo): improve APISIX on-page content and metadata

[Yilialinn]

Summary

• improve titles, descriptions, answer-first openings, image alt text, and internal links across selected APISIX pages
• expand API gateway authentication coverage with Basic and LDAP authentication and clarify OAuth access-token validation
• refresh AI Gateway metadata and hero messaging so the visible introduction naturally covers LLM gateway and LLM proxy, while the description summarizes model routing, resilience, token rate limiting, security, and observability
• remove unsupported statistics, fixed provider pricing, absolute market predictions, and a non-standard MCP header from the AI Gateway comparison article; clarify the respective responsibilities of MCP hosts, servers, and API gateways
• correct the API monetization article to reference limit-count, explain the show_limit_quota_header requirement, and keep metering, billing, and invoicing outside APISIX
• remove FAQPage markup where matching FAQ content is not visible, while retaining valid SoftwareApplication and CollectionPage schemas

This change is based on a deduplicated review of SEMrush Autoimport and Organic Research recommendations for desktop and phone. Suggestions with mismatched intent, unsupported claims, keyword stuffing risk, backlink-only scope, or unavailable media were not implemented.

Pages changed

• AI Gateway landing page and hero
• Homepage and Plugin Hub structured data
• Learning Center: API gateway authentication, API gateways for microservices, APISIX vs Apigee, gRPC, and mutual TLS
• English blogs: API monetization and AI gateway vs API gateway
• Chinese blog: why microservices need an API gateway

Validation

• yarn lint:frontmatter
• targeted ESLint for changed TypeScript files
• website production build for English and Chinese locales
• English blog production build
• targeted Markdown and JSON-LD checks
• text assertions for the required LLM terms and removed unsupported claims
• MCP flow checked against the official protocol architecture and rate-limit behavior checked against the APISIX limit-count documentation
• live-link checks for newly added internal links
• desktop (1440×900) and phone (390×844) visual checks of the AI Gateway hero
• git diff --check

The Chinese blog build remains blocked before content compilation by the repository's existing Docusaurus readingTime configuration validation. Targeted frontmatter and Markdown checks pass, and this diff does not change that configuration.

Monitoring

Re-run SEMrush Autoimport and Organic Research checks on desktop and phone after 14, 28, and 56 days. Use GSC click, impression, CTR, and ranking baselines if available.