Add SEO examples structure — Part 5 of seo-public-surfaces task

[matviychuk]

Summary

Implements Part 5 of docs/todo/seo-public-surfaces-faq-schema-examples-repo.md in full.

README.md restructured (Part 5.1)

• H1: # PlanVault Integration Examples: Connect AI Agents to Production APIs (contains target keywords)
• Why governed AI execution matters — three technical bullet points (fault tolerance, BYOK secrets, HITL approval gates; no internal terms like FSM or PersistentGraphExecutor)
• Examples section with links to all five new sub-directories; each heading contains the search phrase specified in the task
• Self-hosted deployment section with link to planvault.ai/security
• Getting started in 2 days table linking to /docs, /api-docs, /security
• All existing reference implementations table and Runtime API reference preserved

examples/ directory created (Part 5.2)

Directory	H1	Files
01-openapi-import/	Connect Any REST API to AI Agents via OpenAPI Import	README + openapi-sample.yaml (Task Management API, 3 operations, full schemas)
02-langgraph-webhook/	Trigger a LangGraph Agent via PlanVault Webhook	README + webhook_handler.py (FastAPI bridge, LangGraph stub with real invocation comment)
03-mcp-host-nodejs/	Build a Secure MCP Host with Node.js and PlanVault	README + index.ts (MCP stdio server, get_record + list_records) + package.json + tsconfig.json
04-hitl-approval-gate/	Add Human-in-the-Loop Approval Gates to AI Tool Calls	README + tool_with_approval.py (blocking FastAPI tool with approve/reject endpoint)
05-n8n-integration/	Use PlanVault as a Governed AI Execution Step in n8n Workflows	README + n8n-workflow.json (importable, webhook→session→poll loop) + planvault-node.js (Code node snippet)

Each sub-README contains: own H1 with search phrase, problem statement (2–3 sentences), working code snippet, "How it works" section, and links to planvault.ai/docs, /api-docs, /security.

SEO checklist (from task)

• H1 = "PlanVault Integration Examples: Connect AI Agents to Production APIs"
• Each Example heading contains search phrase (LangGraph webhook, MCP host, approval gate, n8n workflow)
• n8n integration is Example examples: session tags + optional externalUserId #5
• No internal terms used as keywords (FSM, PersistentGraphExecutor, AST hashing, "Unlimited integrations")
• Main README cross-links to planvault.ai/docs, /api-docs, /security
• Each sub-README cross-links to relevant planvault.ai pages

Test plan

• Import examples/05-n8n-integration/n8n-workflow.json into a local n8n instance; verify all nodes resolve
• cd examples/03-mcp-host-nodejs && npm install && npx tsc — compiles without errors
• python examples/02-langgraph-webhook/webhook_handler.py — starts on port 8000
• python examples/04-hitl-approval-gate/tool_with_approval.py — starts on port 8001
• Verify all five sub-READMEs render correctly on GitHub (H1, code blocks, links)