feat: implement SubmissionStatistics

[pan93412]

No description provided.

[Copilot]

Pull Request Overview

Implements a new SubmissionStatistics feature that provides comprehensive statistics about user submissions including total questions, attempted questions, solved questions, and breakdown by difficulty level.

• Adds GraphQL schema for submission statistics with nested difficulty breakdown
• Implements resolver logic with database queries for counting questions and submissions
• Provides comprehensive test coverage for various user submission scenarios

Reviewed Changes

Copilot reviewed 6 out of 7 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
graph/question.graphqls	Adds GraphQL schema for SubmissionStatistics and SolvedQuestionByDifficulty types
graph/model/models_gen.go	Generates Go types for the new GraphQL schema definitions
graph/question.resolvers.go	Implements the SubmissionStatistics resolver with database queries
graph/ent.resolvers.go	Refactors resolver type definitions to use type group syntax
graph/submission_statistics_test.go	Comprehensive test suite covering various submission scenarios
go.mod	Adds samber/lo dependency for functional programming utilities

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[Copilot]

Pull Request Overview

Copilot reviewed 6 out of 7 changed files in this pull request and generated no new comments.

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