Remove @material-ui/core dependency from AccordionCard

[talissoncosta]

Problem

web/components/base/accordion/AccordionCard.tsx is the only component using @material-ui/core — specifically Collapse and IconButton. This adds a heavy dependency for a single collapsible card.

Solution

Replace Material UI's Collapse with a CSS transition or native <details>/<summary> element. Remove IconButton usage (use our own Button with theme="icon").

After this change, @material-ui/core can be removed from package.json.

Acceptance criteria

• AccordionCard works identically (expand/collapse animation)
• @material-ui/core removed from dependencies
• No visual regressions

---

Part of the Design System Audit (#6606) · Epic: #6882