65 - Upgrade CRUSH to SLDS-2 (Cosmos) design system

Upgrade the CRUSH managed package (Relationship Maps, Account Plan, Opportunity Plan, White Space, and Settings surfaces) to render correctly under Salesforce Lightning Design System 2 (Cosmos). Scope is multi-release; this Feature Story is the parent — actual work ships through the child tickets listed below.

User Story

As a Salesforce admin at a customer that has adopted (or is adopting) SLDS-2 "Cosmos,"

I want every CRUSH screen — Relationship Map canvas, Account Plan, Opportunity Plan, White Space, and Settings pages — to look correct, operate correctly, and pass an accessibility review under Cosmos,

So that I can roll CRUSH out without it looking broken or off-brand next to the rest of my org's UI.