chore(deps): broad dependency modernization (explicit workflow)

[John Kennedy (jkennedyvz)]

Explicit broad modernization

This PR was created by the explicitly invoked langster-modernize-all-dependencies-explicit workflow. It is a broad dependency modernization, not a routine Dependabot patch.

Scope

• Package root: /
• Ecosystem: Yarn Classic (yarn@1.22.22)
• Target: main
• No application code or GitHub Actions changes

Dependency updates

• @langchain/core: 1.2.3 → 1.2.9
• @langchain/langgraph: 1.4.8 → 1.4.12
• @typescript-eslint/eslint-plugin: 8.65.0 → 8.68.0
• @typescript-eslint/parser: 8.65.0 → 8.68.0
• eslint: 10.8.0 → 10.9.1
• Regenerated the transitive lock graph, including LangGraph checkpoint/SDK and ESLint tooling updates.

Caps and compatibility decisions

• Removed the obsolete **/filelist/minimatch = 5.1.8 resolution. filelist is no longer present in the resolved graph, so the override no longer protects or constrains an installed package.
• Retained TypeScript 6.0.3 rather than moving to 7.0.2: ts-jest@29.4.12 requires TypeScript <7, and @typescript-eslint/parser@8.68.0 supports TypeScript <6.1. This is the newest repository-compatible stable version.
• No compatibility code changes were required.

Validation

• sfw yarn install --frozen-lockfile --ignore-scripts
• yarn build
• yarn lint
• yarn lint:langgraph-json
• yarn format:check
• yarn test --runInBand
• yarn test:int --runInBand
• git diff --check

yarn audit reports 28 high-severity paths for newly disclosed brace-expansion advisories. The same 28 paths reproduce on an untouched origin/main frozen install, so this PR does not introduce them. They are development-tool transitive paths under Jest/glob/minimatch and @eslint/eslintrc; current direct dependency releases do not remove them.

Review hotspots and rollback

• Review the regenerated yarn.lock, especially LangGraph SDK/checkpoint and TypeScript-ESLint transitive changes.
• TypeScript remains intentionally capped at the current compatible major.
• Rollback is a single-commit revert of this PR.