chore(langchain): add ruff rules D (except D100 and D104)

[Christophe Bornet (cbornet)]

See https://docs.astral.sh/ruff/rules/#pydocstyle-d

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1 Skipped Deployment

Project	Deployment	Preview	Comments	Updated (UTC)
langchain	Ignored	Preview		Sep 8, 2025 9:47pm

[codspeed-hq]

CodSpeed WallTime Performance Report

Merging #31994 will not alter performance

_{Comparing cbornet:langchain-ruff-d-fixes (52101f0) with master (017348b)}

⚠️ Unknown Walltime execution environment detected

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

Summary

✅ 13 untouched benchmarks

[codspeed-hq]

CodSpeed Instrumentation Performance Report

Merging #31994 will not alter performance

_{Comparing cbornet:langchain-ruff-d-fixes (52101f0) with master (017348b)}

Summary

✅ 14 untouched benchmarks

[Copilot]

Pull Request Overview

This PR adds additional ruff linting rules from the pydocstyle (D) category except for D100 and D104. The changes focus on enforcing proper docstring formatting standards across the langchain codebase.

Key changes include:

• Standardizing docstring formats to end with periods
• Updating multi-line docstrings to follow proper formatting guidelines
• Removing unnecessary empty lines after docstring opening quotes
• Converting single-line docstrings that spanned multiple lines to proper single-line format

Reviewed Changes

Copilot reviewed 142 out of 143 changed files in this pull request and generated 3 comments.

File	Description
pyproject.toml	Expanded ruff rules from D1 to full D suite, added scripts exclusion
test files (multiple)	Fixed docstring period endings and multi-line formatting
source files (multiple)	Standardized docstring formatting, removed unnecessary empty lines
integration test files	Enhanced docstring documentation with proper Args/Returns sections