chore(main): release 4.0.0

[vig-os-release-app]

🤖 Automated release. Merging this PR creates a tag, which fires the publish workflow (PyPI for py-materials, crates.io for rs-materials).

Release Reviewer Checklist

Check before merging. PR Hygiene CI is intentionally skipped on release-please PRs — these boxes are for the human merging the release.

• Version bump matches expected scope (no surprise major from a stray feat!:)
• CHANGELOG entries read correctly and credit external contributors
• No security-sensitive deps changed without prior review
• Downstream consumers (build123d, ocp_vscode, mat-vis-client) still compatible
• Migration notes (if breaking change) present and linked from CHANGELOG
• All required CI checks green

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4.0.0 (2026-04-19)

⚠ BREAKING CHANGES

• 3.1 — Vis identity split + inline-table finishes + ADR-0002

Added

• 3.1 — Vis identity split + inline-table finishes + ADR-0002 (24d060e)
• 3.1.1 — audit corrections, cache invalidation on identity change, adapter re-exports (aa3f956)
• 3.1.2 — milestone 1 audit follow-ups (13 issues closed) (6a70509)
• 3.2 prep — mat-vis-client 0.5 API adoption (blocked on PyPI publish) (52bde58)
• pixel-diff baselines for visual regression (closes #41's last two checkboxes) (b6f6cce)

Fixed

• test: stale Vis.source_id usage in visual regression test (2e41c7b)

Documentation

• sync README with 3.1 visual-properties shape (d917e6a)

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This PR was generated with Release Please. See documentation.

[gerchowl]

Superseded: v3.2.0 tag was pushed manually after merging #74, triggering release.yml → PyPI. Release-please proposed 4.0.0 because of the feat!: commits in the stack, but we deliberately batched them into 3.2.0 (documented in the hand-written CHANGELOG). Manifest sync in #77 will realign.