ci: SHA-pin all GitHub Actions and add CODEOWNERS (supply-chain harde… #2580

Job	Run time
Rust Unit Tests (macos-latest)	1m 16s
Rust Unit Tests (windows-latest)	2m 35s
Python Tests (ubuntu-latest, py3.14)	59m 30s
Rust Unit Tests (ubuntu-24.04-arm)	1m 31s
Python Tests (windows-latest, py3.11)	1h 0m 8s
Python Tests (macos-latest, py3.11)	35m 10s
Python Tests (ubuntu-24.04-arm, py3.14)	37m 28s
Python Tests (ubuntu-latest, py3.13)	59m 27s
Python Tests (windows-latest, py3.13)	1h 1m 34s
Python Tests (windows-latest, py3.14)	1h 1m 7s
Python Tests (ubuntu-24.04-arm, py3.11)	40m 32s
Python Tests (macos-latest, py3.13)	35m 57s
Python Tests (macos-latest, py3.14)	36m 26s
Pure Python Fallback	1h 31m 33s
Python Tests (ubuntu-latest, py3.11)	1h 9m 32s
Rust Unit Tests (ubuntu-latest)	1m 18s
Python Tests (ubuntu-24.04-arm, py3.13)	36m 38s
	11h 31m 42s

Provide feedback