app-16292: add docs page for the Gizmos plugin

[Devin T. Currie (DTCurrie)]

Adds a docs page covering the Gizmos plugin introduced in #738. Stacks on #738.

Stack

1. Shared ECS traits and helpers (app-16292: shared ECS traits and helpers for entity pose plugins #735)
2. Details refactor (app-16292: refactor Details panel into focused subcomponents #736)
3. Component tweaks (app-16292: small component tweaks to support per-entity pose mutators #737)
4. Gizmos plugin (app-16292: add Gizmos plugin #738)
5. This PR: Gizmos plugin docs

Frontend

• docs/src/content/docs/plugins/gizmos.mdx: new page documenting how to mount <Gizmos />, the available gizmo modes, the read / write properties on the useGizmos hook, and the marker traits exposed via gizmoTraits.
• docs/astro.config.mjs: adds a <Gizmos /> sidebar entry under Plugins, alphabetized between <DrawService /> and <SelectionTool />.

Testing

Docs-only change. The deploy preview build will render the new Plugins > <Gizmos /> page and sidebar entry; no changeset since this does not change runtime behavior.

[changeset-bot]

⚠️ No Changeset found

Latest commit: 25d79b6

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

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[github-actions]

PR Preview Action v1.8.1
🚀 View preview at https://viamrobotics.github.io/visualization/pr-preview/pr-739/
Built to branch gh-pages at 2026-06-03 17:00 UTC. Preview will be ready when the GitHub Pages deployment is complete.

[Devin T. Currie (DTCurrie)]

Claude (@claude) final review

[claude]

Claude finished Devin T. Currie (@DTCurrie)'s task in 2m 10s —— View job

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Final Review

• Gather context and read changed files
• Check previous review comments were addressed
• Review current state of gizmos.mdx
• Post final feedback

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All three prior review issues are resolved:

Previous comment	Status
exit() listed under "Read-only" table	✅ Moved to its own Methods section
No note about coordinate system / reference geometry lacking gizmoTraits entries	✅ <Aside> added
Reference plane / reference geometry field order mismatch with UI	✅ Both sections now match the UI order (placement mode → axis/shape/style)

One nit (inline comment filed on lines 159–161): the bullet list inside the <Aside> uses 4-space indentation. Standard Markdown treats 4 leading spaces as a code block, and MDX parsers typically apply the same rule inside JSX components — so the list may render as <pre> in the deploy preview. The fix is to dedent to 0 spaces; a one-click suggestion is attached inline. Worth a quick check in the deploy preview before merging.

Everything else — usage example, mode key table, per-tool step sequences, useGizmos API table, traits section, and sidebar entry — all match the source accurately. The docs page is otherwise ready to ship.
· Branch