fix: align admin shell with ZORA bounded layout contract

[artiphishle]

Summary

Consume the ZORA owner-side bounded SidebarLayout fix in the Studio admin shell.

Closes #289.

Changes

• remove Studio-local useWindowDimensions() / width < 900 responsive logic
• use ZORA Show with the canonical lg responsive contract for compact vs wide shell composition
• keep the compact Drawer below lg
• use <SidebarLayout sizing="fill"> for the wide bounded shell
• preserve the existing child-owned admin content scrolling contract
• add regression coverage that rejects the old numeric breakpoint and requires fill sizing
• add a patch changeset

Dependency

This code requires @ankhorage/zora >= 2.13.2, which contains ZORA PR #292. The ZORA dependency/lock update is intentionally left for a follow-up commit on this same branch.

Validation target

After the ZORA dependency update:

• desktop admin pages can scroll within the bounded shell
• 900–1023px stays in compact Drawer mode until canonical lg
• compact Drawer behavior remains unchanged
• no duplicate numeric responsive breakpoint exists in Studio