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.

packages/core/src/keybinding.ts

@@ -681,8 +681,6 @@ export type KeyBindingActionId =
   | 'suggestion-next'
   | 'suggestion-prev'
   | 'suggestion-dismiss'
-  | 'suggestion-page-next'
-  | 'suggestion-page-prev'
 
 /** 액션 그룹 (설정 화면 섹션) */
 export type KeyBindingActionGroup = 'voice' | 'window' | 'input'
@@ -786,8 +784,8 @@ export const KEYBINDING_ACTIONS: readonly KeyBindingActionSpec[] = Object.freeze
     descriptionKey: 'keybinding.action.suggestionAccept.desc',
     holdMode: false,
     doublePress: false,
-    // Ctrl+Alt+화살표 계열: 아래/위로 후보 순환, 좌우로 페이지 이동(12개까지
-    // 순차 생성 — 사용자 요청). 화살표를 페이지 이동에 내주기 위해 수락은 Enter로 옮겼다.
+    // Ctrl+Alt+↑/↓ 로 후보를 오가고(페이지는 따라 넘어간다), 수락은 Enter.
+    // 좌우 화살표는 쓰지 않는다 — Intel 그래픽 드라이버의 화면 회전 단축키와 겹친다.
     defaultBindings: [kb(VK.Enter, { ctrl: true, alt: true })]
   },
   {
@@ -808,24 +806,6 @@ export const KEYBINDING_ACTIONS: readonly KeyBindingActionSpec[] = Object.freeze
     doublePress: false,
     defaultBindings: [kb(VK.ArrowUp, { ctrl: true, alt: true })]
   },
-  {
-    id: 'suggestion-page-next',
-    group: 'input',
-    labelKey: 'keybinding.action.suggestionPageNext',
-    descriptionKey: 'keybinding.action.suggestionPageNext.desc',
-    holdMode: false,
-    doublePress: false,
-    defaultBindings: [kb(VK.ArrowRight, { ctrl: true, alt: true })]
-  },
-  {
-    id: 'suggestion-page-prev',
-    group: 'input',
-    labelKey: 'keybinding.action.suggestionPagePrev',
-    descriptionKey: 'keybinding.action.suggestionPagePrev.desc',
-    holdMode: false,
-    doublePress: false,
-    defaultBindings: [kb(VK.ArrowLeft, { ctrl: true, alt: true })]
-  },
   {
     id: 'suggestion-dismiss',
     group: 'input',