[MEDIUM] run_tests reports Success before confirming the TestRunner run actually started

[Daliys]

Problem

run_tests returns status: Success immediately after invoking TestRunnerApi.Execute, even though Unity test execution is asynchronous.

Evidence

• Editor/MCPServerMethods.Editor.cs:81-82 invokes Execute via reflection.
• Editor/MCPServerMethods.Editor.cs:84-91 immediately returns Success and Test run triggered.
• Actual results are collected later through the test-results path, so this response only proves the reflection call did not throw synchronously.

Impact

If a run is already in progress, queued, ignored, or fails asynchronously, the RPC still reports success. Clients must infer failure later by polling and timing out.

Suggested fix

Return a more precise status such as Submitted, register a callback/marker that confirms the run started, or surface a clear already running failure when Unity exposes that state.

Source report

Imported from audit report item: Editor/MCPServerMethods.Editor.cs:84.

[Daliys]

Fixed by #159