Knowledge Base API

I want to integrate with the AgentNDX Knowledge Base API. Please implement a client for it using the spec below.

## Base URL
https://agentndx.com/api/v1

## Authentication
Every request requires this header:
  Authorization: Bearer andx_<your_api_key>

API keys are generated from: AgentNDX dashboard → Settings → API tab (requires Business plan).

## Endpoints

GET  /pages/{pageId}/knowledge
  List all knowledge entries for a page.
  Response: { data: [ { id, tenantId, pageId, type, question, answer, sortOrder, createdAt, updatedAt } ] }

POST /pages/{pageId}/knowledge
  Create a knowledge entry.
  Body: { "question": "string (required, max 2000)", "answer": "string (required, max 5000)", "type": "faq" | "custom" (default "custom") }
  Response 201: { data: { id, tenantId, pageId, type, question, answer, sortOrder, createdAt, updatedAt } }

PUT  /pages/{pageId}/knowledge/{entryId}
  Update a knowledge entry. At least one field required.
  Body: { "question": "string (optional)", "answer": "string (optional)" }
  Response: { data: { ...updated entry } }

DELETE /pages/{pageId}/knowledge/{entryId}
  Delete a knowledge entry.
  Response: 204 No Content

PUT  /pages/{pageId}/content
  Partially update page content (hero text, services list, FAQ section).
  All fields optional — only supplied fields are updated; others are preserved.
  Body: {
    "content": {
      "hero": { "headline": "string", "subheadline": "string", "cta_text": "string", "trust_badges": ["string"] },
      "services": [ { "name": "string", "description": "string", "price_range": "string (optional)" } ],
      "faq": [ { "question": "string", "answer": "string" } ]
    }
  }
  Response: { data: { id, slug, content, updatedAt } }

## Response Envelope
Success: { "data": <payload>, "meta": { "requestId": "req_..." } }
Error:   { "error": { "code": "ERROR_CODE", "message": "Human-readable" }, "meta": { "requestId": "req_..." } }

## Error Codes
401 UNAUTHORIZED           — Missing or invalid API key
402 PLAN_UPGRADE_REQUIRED  — API requires Business plan
404 PAGE_NOT_FOUND         — pageId not found or not yours
404 ENTRY_NOT_FOUND        — entryId not found or not yours
422 VALIDATION_ERROR       — Invalid request body (details in error.details[])
429 RATE_LIMITED           — 120 requests/minute exceeded (Retry-After header included)
500 INTERNAL_ERROR         — Transient server error, safe to retry

## My credentials (fill these in)
API_KEY=andx_YOUR_KEY_HERE
PAGE_ID=YOUR_PAGE_UUID_HERE

## What I want to build
[Describe your use case here — e.g. "a nightly cron job that syncs our menu from a Google Sheet" or "a webhook handler that updates pricing when our CMS publishes"]