Switch blueprints from zipped .blu to plain JSON .blueprint format

[Copilot]

Blueprint files were stored as zipped binary .blu files, making version control diffs impossible. This switches to plain JSON .blueprint files while retaining backward-compatible loading of legacy .blu files.

Storage format change

• BLUEPRINT_SUFFIX changed from .blu to .blueprint
• New LEGACY_BLUEPRINT_SUFFIX = ".blu" constant for backward compat
• saveBlueprint() writes plain JSON directly — no zipping, no temp files
• Removed unused zip() method from BlueprintClipboardManager

Load path: new format first, legacy fallback

// Try plain JSON .blueprint first
File jsonFile = new File(blueprintFolder, fileName + BlueprintsManager.BLUEPRINT_SUFFIX);
if (jsonFile.exists()) {
    return loadBlueprintFromJson(jsonFile, fileName);
}
// Fall back to legacy zipped .blu
File zipFile = new File(blueprintFolder, fileName + BlueprintsManager.LEGACY_BLUEPRINT_SUFFIX);
if (zipFile.exists()) {
    return loadBlueprintFromZip(zipFile, fileName);
}

Updated all file operations to handle both formats

• loadBlueprints() scans for both .blueprint and .blu files
• deleteBlueprint() / renameBlueprint() clean up both formats
• extractDefaultBlueprints() extracts both from addon JARs
• Admin commands (list, load, save, rename) recognize both suffixes in tab completion, existence checks, and file listing

Tests

• Existing tests updated for .blueprint output
• Added tests for plain JSON loading, legacy .blu loading, and format precedence when both exist

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
74.1% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud