docs: rewrite Python SDK and MCP v2 docs for scrapegraph-py PR #84

scrapegraph-py v2 is a complete rewrite (Pydantic v2 + httpx + ApiResult
wrapper + nested resources). Align the docs with the new SDK surface:

Python SDK (sdks/python.mdx):
- Rename Client -> ScrapeGraphAI, AsyncClient -> AsyncScrapeGraphAI
- Show typed Request models (ScrapeRequest, ExtractRequest, SearchRequest,
  CrawlRequest, MonitorCreateRequest, HistoryFilter)
- Document ApiResult[T] pattern (status / data / error / elapsed_ms)
- Document Pydantic format classes (MarkdownFormatConfig, JsonFormatConfig,
  ScreenshotFormatConfig, etc.)
- Document nested resources: sgai.crawl.*, sgai.monitor.*, sgai.history.*
- Document SGAI_API_KEY / SGAI_API_URL / SGAI_TIMEOUT_S / SGAI_DEBUG env vars
- Drop removed methods (markdownify, agenticscraper, sitemap, feedback)

MCP (services/mcp-server.mdx, services/mcp-server/introduction.mdx):
- Base URL: /api/v2 -> /v2 (matches scrapegraph-mcp PR #16 realignment)
- Env vars: SGAI_API_URL / SGAI_TIMEOUT_S (SCRAPEGRAPH_API_BASE_URL legacy)
- Auth: SGAI-APIKEY only (dropped Authorization: Bearer to match SDK)
- Document generate_schema tool
- Expand smartcrawler_initiate formats (markdown/html/links/images/summary/
  branding/screenshot)
- Document FetchConfig passthrough params on all content tools
- Monitor: clarify prompt + output_schema wrap into json format entry

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: VinciGit00