blog: Agent Connectivity Best Practices — expand network-stack post for GSC striking-distance query

[pstayets]

Expands the existing /blog/why-ai-agents-need-network-stack post to target the GSC striking-distance query 'agent connectivity best practices' (pos 5.7, 0 clicks — a title/meta/coverage problem, not a ranking problem).

What changed:

• Retitled to front-load the query: 'Agent Connectivity Best Practices: Why AI Agents Need a Network Stack' (title/meta/llms.txt/blogPosts.json synced).
• New 'Agent Connectivity Best Practices' section: six concrete practices (durable identity+address, assume NAT, encrypt the tunnel, decouple membership from trust, stateful connections, standardized service layer).
• Guardrail sweep: removed invented statistics (88% NAT, 45.6% shared API keys, 100:1, 15x, 4,950 connections) that violated the no-figures rule — replaced with qualitative claims.
• Added 2 new FAQ entries (agent connectivity best practices; why not HTTP) — 6 total in FAQPage schema.
• Added one-command install snippet in Getting Started.
• Internal links: outbound to /learn/what-is-pilot-protocol, /blog/pilot-vs-tailscale-nebula-zerotier-ai-agents, /blog/ai-networking-best-practices-secure-scalable-systems; inbound links added from move-beyond-rest and ai-networking-best-practices posts.
• npm run build and check:plain both pass.