feat: implement Playwright e2e tests infra #73

Job	Run time
Skit / Build	9m 0s
E2E / Playwright E2E	6m 13s
UI / Test	18s
UI / Build	25s
Skit / Test	5m 51s
UI / Lint (TypeScript + ESLint)	32s
Plugins / Format Check	20s
Plugins / Lint (Sherpa-ONNX Plugins)	56s
Plugins / Lint (NLLB)	2m 6s
Plugins / Lint (Whisper)	37s
Skit / Lint (fmt + clippy)	3m 21s
Plugins / Lint (Simple Plugins)	40s
All Checks Passed	4s
	30m 23s

Provide feedback