Fix Python 3.14 compatibility: replace deprecated asyncio.get_event_loop()

[Jscoats]

Summary

Fixes #2829 — All pyatv CLI scripts (atvremote, atvscript, atvlog, atvproxy) crash on Python 3.14 due to asyncio.get_event_loop() raising RuntimeError when no event loop exists in the current thread.

Changes

CLI entry points (4 scripts):

• main(): get_event_loop() + run_until_complete() → asyncio.run()
• Internal functions: removed loop parameter threading, each now calls asyncio.get_running_loop() where needed

Core library (10 files):

• All asyncio.get_event_loop() → asyncio.get_running_loop() (in __init__ methods and async functions)

Additional deprecation fixes:

• asyncio.StreamReader(loop=loop) → asyncio.StreamReader() (param removed in 3.10)
• asyncio.ensure_future(..., loop=loop) → asyncio.ensure_future(...) (param removed in 3.10)
• asyncio.wait([list]) → asyncio.wait(set(...)) in knock.py (list deprecated in 3.11)

Examples (9 files):

• Modernized all examples to use asyncio.run() instead of get_event_loop().run_until_complete()

Tests:

• Updated tests/scripts/conftest.py to call appstart() without loop
• Added test_asyncio_compat.py — regression tests verifying all 4 CLI scripts bootstrap without a pre-existing event loop

What's NOT changed

• Public API (pyatv.scan(), pyatv.connect(), pyatv.pair()) — all signatures preserved
• asyncio.get_running_loop() is available since Python 3.7, so this is safe across all supported versions (3.9+)

Note on asyncio.run() vs loop.run_until_complete()

asyncio.run() additionally finalizes async generators and shuts down the default executor on exit, which is slightly better cleanup behavior. This has no observable effect on CLI usage.

Testing

• All 1248 existing tests pass (0 failures, 6 skipped) + 4 new regression tests
• flake8 clean on all changed files
• grep -rn "get_event_loop" pyatv/ examples/ returns zero matches
• Live tested against Apple TV 4K (tvOS 26.3): scan, connect, play, pause all working

[alexchandel]

Plz merge. This issue makes it impossible to set up pyatv on 3.14.