Prefer WASM on firefox cause WebGPU is incredibly slow there.

docs/Architecture.md

@@ -118,7 +118,13 @@ are the remaining M5 work; see `WorkBreakdown.md`.)
    `navigator.ml` (WebNN) first, then `navigator.gpu?.requestAdapter()` (WebGPU),
    and picks in priority order WebNN → WebGPU → WASM; if pipeline creation on the
    picked device throws, it retries down the same chain (WASM always last). An
-   explicit `"webnn"`/`"webgpu"` preference falls back straight to WASM. It then
+   explicit `"webnn"`/`"webgpu"` preference falls back straight to WASM.
+   Two D-025 refinements: WebGPU is skipped up front when the dtype it would
+   use needs fp16 but the adapter lacks `shader-f16` (Firefox), and a WASM
+   fallback *after* a failed accelerator attempt does not run in-place — the
+   failed attempt pinned ort's thread pool at 1 — but posts `load-restart`,
+   and the UI respawns the worker with an explicit `wasm` load (transcribe
+   posts wait on a ready gate in `App.tsx`, so none are lost). It then
    resolves the catalog's dtype default for the device actually used and creates
    the Transformers.js `automatic-speech-recognition` pipeline.
    Download progress events are forwarded to the UI; the terminal