fix: stabilize default resize snaps

[nynexman4464]

Summary

• replace the render-time snaps = [] default with one stable empty array per hook instance
• keep expand, resize, and _snaps stable when callers omit snap points
• add focused identity regression coverage

Fixes #5275.

Test plan

• fail-first: the omitted-snaps identity test fails on main
• pnpm vitest run packages/core/src/Resizable/useResizable.test.tsx packages/core/src/Resizable/ResizeHandle.test.tsx — 21 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 21, 2026 12:01am

[github-actions]

PR Analysis Report

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Modified Components

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

Metric	Before	After	Delta
Bundle Size (ESM)	N/A	N/A	N/A
Lines of Code	N/A	733	-
Complexity	N/A	Very High (88)	-

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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