feat(caption): let live captions use their own speech model

The speech engine now keeps an auxiliary model next to the dictation model
and transcribes with whichever the request names, reloading it once if the
engine restarted. Settings > STT gains a live-caption model so captions can
run on large-v3-turbo while dictation keeps its own model. The runtime
minimum rises to 1.7.0 because older engines would silently ignore the
model choice.

Suggestion paging moves to Up/Down: the page follows the selection and the
last item waits while more candidates are being generated. The Left/Right
page shortcuts are removed; they did nothing until a page had filled and
clash with Intel's display-rotation hotkeys.

apps/desktop/src/main/services/RuntimeProvisioner.ts

@@ -74,10 +74,11 @@ const RUNTIME_VERSION_FILE = '.runtime-version'
 
 /**
  * 이 앱이 요구하는 런타임 최소 버전. 사이드카 API 가 바뀔 때만 올린다.
- * 1.5.0 — UIA 브리지(`/uia/focus`)가 처음 들어간 사이드카. ffmpeg 는 CLI 가 안정적이라 확인하지 않는다.
+ * 1.5.0 — UIA 브리지(`/uia/focus`). 1.7.0 — 보조 모델 자리(`/load` slot, `/transcribe` model_id).
+ * ffmpeg 는 CLI 가 안정적이라 확인하지 않는다.
  */
 const RUNTIME_MIN_VERSION: Record<RuntimeComponent, string | null> = {
-  sidecar: '1.5.0',
+  sidecar: '1.7.0',
   ffmpeg: null
 }
 const DOWNLOAD_TIMEOUT_MS = 120_000