Optimize max peak memory usage and add warnings on mobile for higher models

docs/WorkBreakdown.md

@@ -255,6 +255,15 @@ Notes (M5):
       WebGPU EP on Firefox completes but runs far slower than WASM, so
       "auto" skips WebGPU on Firefox (D-026, explicit selection still
       honored — retest on ort bumps).
+- [x] Mobile OOM crash on Medium+ model loads (D-027) — patched
+      `@huggingface/transformers` (`bun patch`) to load the encoder/decoder
+      sessions sequentially instead of concurrently, roughly halving
+      load-time peak memory for every model; added a mobile UA +
+      `deviceMemory` warn/confirm gate (`src/lib/mobileMemoryGuard.ts`)
+      before any browser-engine load whose estimated peak
+      (`estimatePeakLoadBytes`) is risky on a phone/tablet, covering the
+      explicit Download button and the lazy auto-load on file-drop/live-start
+      alike.
 - [ ] Basic a11y pass (keyboard, focus, aria on progress/live transcript)
 - [ ] Production build + `bun start` deployment check; README for deployers