fix(literal): use Object.is so literal(NaN) accepts NaN (#1529)

[sanjibani]

Closes #1529.

Bug

`literal(NaN)` was an unsatisfiable schema: the runtime value check used `===`, and `NaN === NaN` is `false`, so every input - including the `NaN` the schema was constructed from - failed validation.

`Literal` is typed as `bigint | boolean | number | string | symbol`, and `literal(NaN)` is a fully type-checked construction. The sibling `picklist` schema compares with `Array.includes` (SameValueZero) and already returns `true` for `picklist([NaN])` against `NaN`, so the two schemas gave opposite answers for the same value.

v.parse(v.literal(NaN), NaN); // throws: Invalid type: Expected NaN but received NaN
v.is(v.literal(NaN), NaN);    // false
v.is(v.picklist([NaN]), NaN);  // true

Fix

Switch the single comparison in `library/src/schemas/literal/literal.ts` from `===` to `Object.is`. `Object.is(NaN, NaN)` is `true`, so `literal(NaN)` now accepts `NaN`.

This matches the equality migration already in flight: #1517 moves `_merge` (used by `intersect`) to `Object.is`, and #1477 moves `value` / `notValue` / `values` / `notValues` to `Object.is`. Neither of those touched `literal`, so this closes the same NaN gap one layer up.

Trade-off

Like #1517 and #1477, `Object.is` also distinguishes `+0` from `-0` (they are equal under `===` and SameValueZero). The `Literal` union is `bigint | boolean | number | string | symbol`; `-0` is a valid `number`, and `literal(-0)` and `literal(0)` would still be distinguishable as different construction values but would accept each other's runtime values. The previous `===` already collapsed `+0` and `-0` at construction time, so the new behavior is a strict relaxation of `-0` distinguishability, not a tightening of any contract.

Tests

Added two regression tests:

• `for NaN literal` in the no-issues suite: `literal(NaN)` accepts `NaN`. Fails against the unpatched code (`NaN === NaN` is `false`).
• `for invalid NaN literal` in the issues suite: `literal(NaN)` still rejects other numbers, booleans, strings, symbols, etc. (`NaN` is the only value that should match.)

2 files changed, +35/-1.

Summary by CodeRabbit

• Bug Fixes
  • Improved literal matching for edge-case values like NaN and signed zero.
  • literal(NaN) now accepts NaN correctly and returns no validation issues.
  • Invalid values still produce the expected validation error, including the correct displayed expected value.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between 32247b3 and bc98085.

📒 Files selected for processing (2)

• library/src/schemas/literal/literal.test.ts
• library/src/schemas/literal/literal.ts

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Walkthrough

The literal schema's runtime comparison was changed from strict equality (===) to Object.is when checking whether a dataset value matches the configured literal. This resolves an issue where literal(NaN) rejected NaN due to NaN === NaN evaluating to false. Two tests were added: one confirming literal(NaN) accepts NaN without schema issues, and another confirming literal(NaN, 'message') rejects non-NaN inputs with an issue expecting 'NaN'.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: switching literal matching to Object.is for NaN support.
Linked Issues check	✅ Passed	The changes satisfy issue #1529 by using Object.is in literal matching and adding regression tests for NaN behavior.
Out of Scope Changes check	✅ Passed	The PR stays within scope, ограничing changes to the literal NaN fix and related regression tests.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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[cubic-dev-ai]

No issues found across 2 files

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