dsh-accessibility v0.1.0-beta.5

This beta expands the companion accessibility audit from 14 to 17 structural checks.\n\nNew diagnostics:\n- Heading hierarchy and missing primary-heading checks.\n- List and list-item semantic consistency.\n- Nested interactive-control detection.\n\nThe bilingual guidance now points to the dsh-v0.1.1-rc.2-a11y.4 core candidate and clearly separates automated conformance from human assistive-technology certification.\n\nValidation passed on Ubuntu, macOS, and Windows with Node 22.19 and Node 24.x. Unit tests, typecheck, build, and package tarball inspection are green.\n\nInstall this prerelease with:\n\ndsh plugin --profile web add @oh-my-dsh/dsh-accessibility@0.1.0-beta.5