[Docs] Tools: document the new portlet and the UI/UX changes

Goal

Document the Tools portlet so an admin can find it, understand what it controls, and know where granting lives — and so a developer knows how to opt in and how to roll back.

Scope

User docs

• What Tools is: the surface that defines the backend navigation — the sections in the left menu, the tools inside each section, and the order of both.
• The boundary that matters most: Tools is the master list. Putting a tool in a section does not give anyone access to it. Access is granted per role in Settings → Roles & Tools. Say this early and plainly, because it is the question every admin will have.
• Where the screen lives and how to reach it.
• Sections: creating one from a name and an icon, renaming it, changing its icon, deleting it, and dragging to set its position in the navigation.
• Tools in a section: checking a tool to add it, unchecking or using the remove control to take it out, dragging to set the order inside the section, and searching the catalog.
• Custom content tools: what a tool created through New Tool actually is — a filtered content list — and what each field does, including the id and when to change it, the content to display, and the difference between the List and Card data view modes.
• What deleting a section costs, per the spike's findings, so the confirmation dialog is not the first place an admin learns it.
• Where the equivalent settings used to live for anyone coming from the older screen.

Developer note

• The Beta portlet id is tools-beta, display name Tools (Beta), served at /#/c/tools-beta.
• It ships opt-in: not in any default layout and not added by an UpgradeTask. An admin adds it through Add Portlet.
• Rolling back means removing it from the layout. No code change, no redeploy, and nothing about the existing navigation is modified by installing it.
• The /v1 endpoints the portlet uses, and the note that the equivalent RoleAjax DWR methods remain in place for the Dojo screen.

Inputs

• Epic #37351 and the spike's artifacts
• The shipped portlet on a running instance
• Design: https://claude.ai/design/p/879ff4e6-1b23-486d-9926-327709e91953?via=share&file=Tools.dc.html (internal — auth required)

Definition of Done

• User docs published, covering every surface and action the portlet ships.
• The Tools versus Roles & Tools boundary is stated explicitly, near the top.
• The developer note covers the Beta portlet id, how to opt in, and how to roll back.
• Screenshots match the shipped UI, not the design mockups.

Refs #37351