docs: add AI/ML API integration

[D1m7asis]

Description:
Introduces documentation notebooks for AI/ML API integration covering the following use cases:

• Chat models (ChatAimlapi)
• Text completion models (AimlapiLLM)
• Provider usage examples
• Text embedding models (AimlapiEmbeddings)

Additionally, adds the langchain-aimlapi package entry to libs/packages.yml for package management.

This PR aims to provide a comprehensive starting point for developers integrating AI/ML API models with LangChain via the new langchain-aimlapi package.

Issue: N/A

Dependencies: None

Twitter handle: @aimlapi

---

To-Do Before Submitting PR:

• Run make format
• Run make lint
• Confirm all documentation notebooks are in docs/docs/integrations/
• Double-check libs/packages.yml has the correct repo path
• Confirm no pyproject.toml modifications were made unnecessarily

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Project	Deployment	Preview	Comments	Updated (UTC)
langchain	Canceled			Sep 12, 2025 2:50am

[codspeed-hq]

CodSpeed WallTime Performance Report

Merging #32430 will improve performances by 16.54%

_{Comparing D1m7asis:master (e6ed5f7) with master (338d3d2)}

⚠️ Unknown Walltime execution environment detected

Using the Walltime instrument on standard Hosted Runners will lead to inconsistent data.

For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

Summary

⚡ 2 improvements
✅ 11 untouched

Benchmarks breakdown

	Benchmark	BASE	HEAD	Change
⚡	test_import_time[InMemoryVectorStore]	688.8 ms	617 ms	+11.63%
⚡	test_import_time[RunnableLambda]	560.7 ms	481.1 ms	+16.54%

[codspeed-hq]

CodSpeed Instrumentation Performance Report

Merging #32430 will not alter performance

_{Comparing D1m7asis:master (e6ed5f7) with master (338d3d2)}

Summary

✅ 14 untouched