refactor: formalize C ABI codec registry via as_c_name/from_c_name #898

Job	Run time
Plugins / Format Check	20s
Plugins / Lint (NLLB)	2m 31s
Skit / Test (GPU)	1m 41s
Plugins / Lint (Whisper)	1m 3s
Plugins / Lint (Simple Plugins)	44s
UI / Test	29s
UI / Lint (TypeScript + ESLint)	36s
Plugins / Lint (Sherpa-ONNX Plugins)	1m 18s
UI / Knip (unused code)	19s
Skit / Lint (fmt + clippy)	3m 57s
Skit / Build	10m 12s
Skit / Test	7m 32s
E2E / Playwright E2E	14m 28s
UI / Build	15s
All Checks Passed	1s
	45m 26s

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