feat(docker): add batteries-included demo image (CPU) #84

Job	Run time
Skit / Lint (fmt + clippy)	2m 44s
UI / Test	19s
Skit / Test	6m 45s
E2E / Playwright E2E	6m 31s
UI / Build	33s
UI / Lint (TypeScript + ESLint)	30s
Plugins / Lint (NLLB)	2m 14s
Plugins / Lint (Sherpa-ONNX Plugins)	46s
Plugins / Format Check	18s
Plugins / Lint (Whisper)	43s
Plugins / Lint (Simple Plugins)	36s
Skit / Build	8m 50s
All Checks Passed	3s
	30m 52s

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