🪲 BUG-#211: Fix async task execution to reuse event loops

[FernandoCelmer]

Description

Fix Action._call_func() to properly handle async functions by reusing existing event loops instead of always creating new ones with asyncio.run().

Issue: 📌 ISSUE-#211

Changes

• Replace asyncio.iscoroutinefunction with inspect.iscoroutinefunction (removes Python 3.16 deprecation warning)
• Add 3 async execution paths:
  • No running loop → asyncio.run() (creates new loop)
  • Loop exists but not running → loop.run_until_complete() (reuses loop)
  • Loop is running (Jupyter/IPython) → ThreadPoolExecutor fallback
• Move concurrent.futures import to top-level
• Simplify flow with early return for sync functions

Type of change

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes