refactor(run): migrate project preparation to Vix Engine

[GaspardKirira]

Summary

Replace all project-specific configure and build branches in vix run with one
Vix Engine request.

Requirements

• Support CMake preset projects.
• Support generated vix.app projects.
• Support standard CMake projects.
• Support clean and check-only requests.
• Resolve the selected executable artifact.
• Remove duplicate build-directory resolution.

Acceptance criteria

• Every project path uses Vix Engine.
• Preset projects remain supported.
• Generated projects remain supported.
• Standard CMake projects remain supported.
• vix run contains no independent build pipeline.