Migrate lint/format tooling to Ruff, update CI matrix, and stabilize cross-platform/firefox tests #61

Job	Run time
test_config (previous, 3.12.12, 7.3.2, 4.38.0, chrome)	5m 39s
test_config (latest, 3.13.10, 7.4.1, 4.39.0, chrome)	5m 45s
test_config (older_rf_version, 3.11.14, 6.1.1, 4.37.0, chrome)	5m 50s
test_config (latest, 3.13.10, 7.4.1, 4.39.0, firefox)	8m 38s
	25m 52s

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