feat(engine): make AddNode non-blocking with async node creation (#286) #1044

Job	Run time
E2E / Playwright E2E	16m 35s
Plugins / Format Check	17s
Skit / Test (GPU)	2m 14s
Plugins / Lint (NLLB)	2m 17s
Plugins / Lint (Simple Plugins)	1m 5s
Skit / Lint (fmt + clippy)	3m 35s
Plugins / Lint (Sherpa-ONNX Plugins)	55s
Skit / Build	13m 49s
UI / Lint (TypeScript + ESLint)	38s
UI / Test	25s
UI / Build	18s
Plugins / Lint (Whisper)	42s
UI / Knip (unused code)	21s
Skit / Test	10m 7s
All Checks Passed	4s
	53m 22s

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