fix: guard extension.requires against non-iterable values on iOS 26.5 JavaScriptCore

[Copilot]

iOS 26.5's JavaScriptCore can produce a plain object {} for extension.requires at runtime. Calling Array.from({}) in ExtensionManager.setupExtensions throws an uncatchable TypeError: {} is not iterable, crashing editor initialization.

Changes — packages/editor/src/ExtensionManager.ts:

• Replace Array.from(extension.requires) with an Array.isArray() guard, falling back to [] for non-array values — consistent with the identical guard already present at line 220 of the same file

// Before
const childExtensions = Array.from(extension.requires).filter((e) =>
  typeof e !== 'string'
);

// After
const requires = Array.isArray(extension.requires) ? extension.requires : [];
const childExtensions = requires.filter((e) => typeof e !== 'string');

Related Issue

Checklist

• I have read CONTRIBUTING.md

• I ran deno task postinstall

• My commits follow Conventional Commits

• I added tests or documentation if needed

• I have performed a self-review of my code

• All commits are meaningful (no trivial fix: typo)

• I have added tests that prove my fix is effective or that my feature works

Type of change:

• feat
• fix
• chore
• docs
• test
• refactor
• ci
• build