fix: stabilize useLayer references

[nynexman4464]

Summary

• keep the context trigger ref returned by useLayer stable across unrelated rerenders
• memoize the context and fixed API objects from their exposed members
• preserve updates when callbacks, open state, or render behavior actually change
• add regression coverage for stable refs and return objects

Fixes #5271.

Test plan

• fail-first: three identity tests fail on main
• pnpm vitest run packages/core/src/Layer/useLayer.test.tsx — 46 passed
• pnpm -F @astryxdesign/core build
• focused ESLint, formatting, sync, and changeset checks

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Project	Deployment	Actions	Updated (UTC)
astryx	Ready	Preview	Aug 20, 2026 11:48pm

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PR Analysis Report

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Modified Components

Layer _{(@astryxdesign/core)} · View in Storybook

Metric	Before	After	Delta
Bundle Size (ESM)	N/A	N/A	N/A
Lines of Code	N/A	797	-
Complexity	N/A	Very High (86)	-

Bundle Size Summary

Package	Size (ESM)	Size (CJS)	Gzipped
@astryxdesign/core	N/A	4.8KB	1.2KB

Accessibility Audit

Status: No accessibility violations detected.

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