feat: implement unified project test orchestration

[dDevAhmed]

Summary

Implements CLI-032 by adding stellarforge test for supported generated Node.js and Stellar smart-contract projects.

This PR is temporarily stacked on CLI-031 so it can reuse the validated safe subprocess supervisor while the repository-level Dependency Graph setting remains the only external blocker on preceding PRs.

Included

• registers stellarforge test
• detects generated Node.js projects with a package.json test script
• detects generated Cargo smart-contract workspaces
• invokes Node tests via npm run test and contract tests via cargo test
• never executes package script text directly
• reuses shell-free subprocess supervision and filtered child environment
• streams prefixed child stdout/stderr
• converts failing child tests into non-zero subprocess CLI failures
• rejects unsupported/malformed project layouts with actionable guidance
• unit coverage for Node/Cargo resolution and malformed layouts
• command-level coverage for successful output and failing-child semantics

Security

• executable + argument arrays only
• no shell interpolation
• no arbitrary test command field execution
• no broad environment inheritance
• no swallowed child failures

Closes #35