Fix test file recreation threading issue in CheckAction

[meanmail]

Overview

Test file recreation (anti-cheating mechanism) blocks background threads unnecessarily during task checking, potentially causing performance issues.

Location

File: intellij-plugin/hs-core/src/org/hyperskill/academy/learning/actions/CheckAction.kt
Function: recreateTestFiles (lines 167-194)

Problem

Test file recreation is done synchronously during check with invokeAndWaitIfNeeded + runWriteAction. This blocks the background thread that's running the check operation.

override fun run(indicator: ProgressIndicator) {
    // Running on background thread
    recreateTestFiles(project, task) // But this blocks with invokeAndWaitIfNeeded
}

What needs to be fixed

• The operation is already on a background thread (line 133 run(indicator: ProgressIndicator)) but uses invokeAndWaitIfNeeded which blocks unnecessarily
• Consider using runWriteActionAndWait or restructuring to avoid blocking
• Add proper error handling for individual file recreation failures (currently just logs warnings)
• The same pattern exists in FrameworkLessonManagerImpl.recreateTestFiles (lines 219-245) - fix both locations consistently

Tests understanding of

• Background task threading in IntelliJ Platform
• When to use invokeAndWaitIfNeeded vs other patterns
• Write action requirements and proper usage
• Progress indicator usage
• Command processor for undo/redo support
• Anti-cheating mechanisms in educational plugins

Validation

• Create a task with many test files
• Run checker repeatedly and measure performance
• Ensure smooth operation without blocking
• Verify files are still recreated correctly

Estimated time

3-4 hours