Feat/modernize langchain integration crawl tools

[daveomri]

Summary

Third PR on top of feat/modernize-langchain-integration; builds on the [native components PR](https://github.com/apify/langchain-apify/tree/feat/modernize-langchain-integration-native-components) and adds the Search & Crawling Actor tools layer: four new BaseTool subclasses wrapping search, maps, video, and e-commerce Actors. Upcoming PR will fold this together with social-media tools and documentation onto [feat/modernize-langchain-integration](https://github.com/apify/langchain-apify/tree/feat/modernize-langchain-integration) before merging to main.

New code: ~426 lines — Tests: ~337 lines

Note on scope: This PR is intentionally scoped to the four Search & Crawling Actor tools called out in US-4 (RAG Web Browser, Google Maps, YouTube, E-commerce). Social-media Actor tools and the integration documentation will land as follow-up PRs.

---

• ApifyRAGWebBrowserTool ([_actor_tools.py](langchain_apify/_actor_tools.py))
  • Wraps apify/rag-web-browser. Returns JSON with run metadata (run_id / status / dataset_id / timestamps) and items (crawled-page dicts). Distinct from ApifySearchRetriever (which returns LangChain Document objects); this tool returns JSON for agent tool-calling.
• ApifyGoogleMapsTool ([_actor_tools.py](langchain_apify/_actor_tools.py))
  • Wraps compass/crawler-google-places. Required query, optional max_results (default 10) and language (ISO code). Returns JSON with run metadata and items (place dicts).
• ApifyYouTubeScraperTool ([_actor_tools.py](langchain_apify/_actor_tools.py))
  • Wraps streamers/youtube-scraper. Required search_query, optional search_type: Literal['search', 'video', 'channel'] (default search), max_results (default 10). Tight Literal at the LLM boundary, loose str + runtime ValueError at the _client.py boundary so direct callers get the same protection.
• ApifyEcommerceScraperTool ([_actor_tools.py](langchain_apify/_actor_tools.py))
  • Wraps apify/e-commerce-scraping-tool. Required url, optional max_results (default 20). Bare-URL design intentionally keeps the LLM-facing surface minimal; selector hints can be added later if real users hit empty-result issues.
• APIFY_SEARCH_TOOLS convenience list
  • New list[type[BaseTool]] exported alongside APIFY_CORE_TOOLS and APIFY_ACTOR_TOOLS for selective agent binding: [ApifyRAGWebBrowserTool, ApifyGoogleMapsTool, ApifyYouTubeScraperTool, ApifyEcommerceScraperTool].
• ApifyToolsClient additions ([_client.py](langchain_apify/_client.py))
  • Three new methods (google_maps_search, youtube_scrape, ecommerce_scrape) and one rename + signature change: rag_web_search → rag_web_browser_search, now returning (run, items) like the other helpers so the tool layer can build _run_meta(run). All four reuse the existing run_actor_and_get_items plumbing — transport-error wrapping and _check_run_status come for free.
• ApifySearchRetriever ([retrievers.py](langchain_apify/retrievers.py))
  • Single call site updated to consume the new tuple return (_, items = self._client.rag_web_browser_search(...)); behaviour and Document shape are unchanged.
• Backward compatible
  • No changes to public API of any pre-existing class. ApifyActorsTool / ApifyDatasetLoader / ApifyWrapper untouched. The rag_web_search rename is internal — only the retriever consumed it, and that's updated in-tree.
• Tests
  • 35 new unit tests covering: input-mapping per helper (asserts Actor ID + run_input keys), youtube_scrape enum validation, happy-path JSON shape per tool, parametrized _TOOL_INVOCATIONS battery covering RuntimeError → ToolException, empty-dataset, handle_tool_error=True swallow, missing-token, plus inheritance / metadata / APIFY_SEARCH_TOOLS membership. Existing test_retrievers.py tests rewired for the new tuple-return helper.

Review strategy

Suggested reading order:

1. [_client.py](langchain_apify/_client.py): the three new ApifyToolsClient methods plus the rag_web_search → rag_web_browser_search rename — each follows the same pattern as the native-components methods.
2. [_actor_tools.py](langchain_apify/_actor_tools.py): the four new _ApifyGenericTool subclasses and their input schemas (homogeneous; once one clicks the rest read fast).
3. [retrievers.py](langchain_apify/retrievers.py): tiny diff for the tuple-unpack at the two call sites.
4. init.py: new APIFY_SEARCH_TOOLS list and __all__ additions.
5. Tests last: grouped by the module they cover.

Merge strategy

This PR targets feat/modernize-langchain-integration, not main. It depends on the [native components PR](https://github.com/apify/langchain-apify/tree/feat/modernize-langchain-integration-native-components) being merged first — _actor_tools.py extends the file introduced there and consumes _run_meta / _ApifyGenericTool from tools.py. Once native components is merged into the integration branch, this PR will be rebased and opened for review. Social-media tools and docs will follow as separate PRs on the same integration branch before the final merge to main.