fix(array): compare dates by value in indexOf() so pull() removes them

[giaBaoJS]

Summary

pull() on a [Date] array does not remove the date from the document, even though the $pullAll it registers does remove it from the database.

pull() looks for matches with this.indexOf.call(values, mem), and MongooseArray#indexOf() compares with ==. That works for numbers and strings, and ObjectIds are converted to strings first, but two Date objects are only == when they are the same instance. The value passed to pull() is cast to a new Date, so it never matches.

The local array and the database then disagree after save(). It gets worse when the same array is also pushed to before saving: $pullAll and $push can't be combined, so the atomics fall back to $set of the local array, and the date that was pulled is written back.

addToSet() already handles this case with its own date branch that compares +d === val, so addToSet() and pull() currently disagree about whether two equal dates are the same value. This PR does the same timestamp comparison in indexOf(). pull() and remove() pick it up through their existing call, and includes() / indexOf() now find dates by value too, the same way they already find ObjectIds by value.

Not changed here: Decimal128, Double, UUID and Buffer arrays also compare by reference, in both addToSet() and pull(). Unlike dates, neither method has an equality rule for those types today, so that needs a per-type decision rather than making the two methods agree. Happy to follow up if you want that.

Examples

const Test = mongoose.model('Test', new Schema({ dates: [Date] }));
const { _id } = await Test.create({ dates: [new Date('2026-01-01'), new Date('2026-02-01')] });

const doc = await Test.findById(_id);
doc.dates.pull(new Date('2026-01-01'));
doc.dates.length; // 2 before, 1 after

doc.dates.push(new Date('2026-03-01'));
await doc.save();
(await Test.findById(_id).lean()).dates;
// before: [2026-01-01, 2026-02-01, 2026-03-01]
// after:  [2026-02-01, 2026-03-01]

Added two tests in test/types.array.test.js: one under pull() that covers both the local array and the saved result after pull() + push(), and one under indexOf() for indexOf() / includes() on dates, including fromIndex and a Mixed array holding the same timestamp as a number (which must still not match a Date). Both fail on master and pass with this change.