feat(phase7): pattern search, health check, keyboard shortcuts

- KeyList: pattern input for Redis MATCH, local filter, Go button
- ConnectionStore: health check interval (5s ping), healthOk state
- StatusBar: health indicator (unstable = yellow pulse)
- RedisService: ping, isConnected methods
- Sidebar: Delete key (Del), deselect (Esc), refresh (F5)
- useKeyboard: expanded shortcut map

src/preload/index.ts

@@ -110,6 +110,10 @@ const electronAPI = {
       ipcRenderer.invoke('redis:renameKey', id, oldKey, newKey),
     existsKey: (id: string, key: string): Promise<boolean> =>
       ipcRenderer.invoke('redis:existsKey', id, key),
+    ping: (id: string): Promise<string> =>
+      ipcRenderer.invoke('redis:ping', id),
+    isConnected: (id: string): Promise<boolean> =>
+      ipcRenderer.invoke('redis:isConnected', id),
   },
 }