refactor(api): migrate console site responses to BaseModel

[ai-hpc]

Part of #28015

Summary

Migrate response marshalling in api/controllers/console/app/app_import.py from Flask-RESTX response models to Pydantic BaseModel/ResponseModel schemas registered with register_schema_models().

Checklist

• This change requires a documentation update, included: Dify Document
• I understand that this PR may be closed in case there was no previous discussion or issues. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.
• I ran make lint and make type-check (backend) and cd web && pnpm exec vp staged (frontend) to appease the lint gods

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[Copilot]

Pull request overview

Migrates the console app import endpoints in api/controllers/console/app/app_import.py from Flask-RESTX response models to Pydantic BaseModel/ResponseModel schemas registered via register_schema_models(), aligning response documentation and serialization with the newer schema approach used elsewhere in the console API.

Changes:

• Added Pydantic response schemas (AppImportResponse, AppImportCheckDependenciesResponse, LeakedDependencyResponse) and registered them with console_ns.
• Updated RESTX @response decorators to reference the new schema models.
• Updated endpoint return paths to validate into response models before model_dump(mode="json").

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[Copilot]

LeakedDependencyResponse.value is annotated as Any, but when validating from CheckDependenciesResult it will receive PluginDependency.value objects (nested Pydantic models). To avoid accidentally returning a non-JSON-serializable object (depending on how Any is serialized), consider normalizing value to a plain dict (e.g., type it as dict[str, Any] and/or add a validator that converts BaseModel values via model_dump(mode="json")).

[Copilot]

AppImportCheckDependenciesResponse.model_validate(result) relies on attribute access; if check_dependencies() ever returns a dict/model_dump()-style object (as some tests/mocks do), this will fail. A more robust approach is to validate from result.model_dump(mode="json") (or from the dict directly) before dumping the response.

Suggested change

	return AppImportCheckDependenciesResponse.model_validate(result).model_dump(mode="json"), 200
	result_data = result if isinstance(result, dict) else result.model_dump(mode="json")
	return AppImportCheckDependenciesResponse.model_validate(result_data).model_dump(mode="json"), 200