`toEqual` behavior with symbol properties with undefined values

Describe the bug

The behavior of toEqual with objects with symbol properties and undefined values is inconsistent with the behavior of toEqual with objects with regular (non-symbol) properties and undefined values.

With regular properties, undefined is treated as equivalent to not present, so expect({ a: undefined }).toEqual({}) passes. With symbol properties, they're not equivalent, so expect({ [sym]: undefined}).toEqual({}) fails.

The discrepancy appears to be caused by this logic: keys() checks hasKey (which defaults to hasDefinedKey - i.e., not undefined) for enumerable string properties but omits it for symbol properties.

I can submit a PR if there's interest.

Reproduction

https://stackblitz.com/edit/vitest-dev-vitest-ttuzge3r?file=test%2Fbasic.test.ts,package.json&initialPath=__vitest__

System Info

System:
    OS: macOS 15.5
    CPU: (10) arm64 Apple M1 Pro
    Memory: 155.73 MB / 16.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 22.17.1 - ~/.nvm/versions/node/v22.17.1/bin/node
    Yarn: 4.9.2 - /opt/homebrew/bin/yarn
    npm: 10.9.2 - ~/.nvm/versions/node/v22.17.1/bin/npm
    bun: 1.2.19 - /opt/homebrew/bin/bun
  Browsers:
    Chrome: 138.0.7204.169
    Edge: 138.0.3351.95
    Safari: 18.5
    Safari Technology Preview: 26.0
  npmPackages:
    vitest: ^3.2.4 => 3.2.4

Used Package Manager

yarn

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the bug.

Start in packages/expect/src/jest-utils.ts around line 283 and run the StackBlitz reproduction to confirm the difference between symbol and regular properties with undefined values. Done means toEqual treats equivalent symbol-property cases consistently, with regression coverage for the reported behavior.