fix: defer active compile directory cleanup

[ttbombadil]

Summary

• prevents SandboxRunner.stop() from cleaning the active sketch/output directory while local compilation is still in progress
• preserves cleanup of unrelated stale tracked directories
• reuses the existing deferred cleanup path after compilation settles
• adds deterministic regression coverage for stop-during-compile and normal cleanup behavior

Root cause

markTempDirForCleanup() already defers cleanup while isCompiling or localCompiler.isBusy is true.

However, SandboxRunner.stop() subsequently iterated all directories returned by getCreatedSketchDirs() and called attemptCleanupDir() directly.

That bypassed the compile guard and could rename the active directory to .cleanup while compilation still needed it.

Observed production log symptom:

[RaceCondition] Output directory vanished before g++ spawn

Fix

While compilation is active, the direct tracked-directory cleanup loop skips only the active compile directory.

Other stale tracked directories continue to be cleaned.

After the compile settles, the existing deferred cleanup path processes the active directory and clears its tracking.

Regression coverage

• stop during active compilation:
  • active compile directory remains available
  • stale tracked directory is still cleaned
  • deferred cleanup remains pending
  • active directory is cleaned exactly once after compile completion
• stop without active compilation:
  • existing cleanup behavior remains unchanged

The race test uses a controlled Promise and no timing sleeps.

Validation

• focused SandboxRunner + FilesystemHelper tests: 42/42 PASS
• npm run check: PASS
• npm test: 2113/2113 PASS
• npm run test:coverage: PASS
  • Lines: 86.53%
  • Statements: 84.44%
  • Functions: 85.16%
  • Branches: 73.24%
• npm run test:integration: 13 PASS, 1 SKIP
• git diff --check: PASS

Scope

• no CI changes
• no timeout changes
• no retry changes
• no rate-limit changes
• no changes to UnoSim_Test