types(plugin): allow passing model with custom TStatics into Schema.prototype.plugin()

[vkarpov15]

Fix #16086

Summary

Added a wider plugin() function that lets you pass in a plugin that operates on any schema.

Examples

[Copilot]

Pull request overview

This pull request updates Mongoose’s TypeScript typings to make Schema#plugin() accept plugins whose schema parameter is typed as a generic Schema even when the schema’s model type includes custom statics.

Changes:

• Add a fallback overload for Schema#plugin() that uses a base Model<DocType, ...> model type.
• Add a TypeScript type test that reproduces and validates the intended schema.plugin(plugin) behavior for a schema with a custom model interface.

Reviewed changes

Copilot reviewed 1 out of 2 changed files in this pull request and generated no comments.

File	Description
types/index.d.ts	Adds an additional Schema#plugin() overload to improve plugin compatibility with schemas using custom model typings.
test/types/plugin.test.ts	Adds a compile-time type test case (gh16086) covering the new overload scenario.