Update project dependencies

[ejsmith]

Summary

• update the docs stack to Mermaid 11.16.0, VitePress 2.0.0-alpha.18, and vitepress-plugin-llms 1.13.4
• update @std/path to 1.1.6 and refresh both lockfiles
• update official GitHub Actions to their current major releases
• make the docs workflow reproducible with npm ci --force and Node.js 24
• incorporate the transitive updates from Dependabot PRs Bump markdown-it from 14.1.1 to 14.2.0 in /docs #25, Bump brace-expansion from 5.0.6 to 5.0.7 in /docs #28, Bump linkify-it from 5.0.0 to 5.0.2 in /docs #29, Bump dompurify from 3.4.5 to 3.4.12 in /docs #30, Bump postcss from 8.5.15 to 8.5.24 in /docs #34, and Bump js-yaml from 3.14.2 to 3.15.0 in /docs #35

Details

vitepress-plugin-mermaid is already at its latest release (2.0.17), but its peer range has not yet been updated for VitePress 2 alpha. The docs install therefore keeps --force; the generated site builds successfully with VitePress 2.0.0-alpha.18.

The refreshed lockfile includes markdown-it 14.3.0, brace-expansion 5.0.8, linkify-it 5.0.2, DOMPurify 3.4.12, PostCSS 8.5.24, and js-yaml 4.3.0.

Validation

• deno task format-check
• deno task lint
• deno task check
• deno task test (200 tests)
• npm ci --prefix docs --force
• npm run build --prefix docs
• npm audit --prefix docs --audit-level=low (0 vulnerabilities)
• deno outdated --latest (no updates available)
• git diff --check