feat(x): add Caffeinate toggle to keep the system awake

Adds a Caffeinate switch (Settings → Mobile channels) that uses
Electron's powerSaveBlocker ('prevent-app-suspension', equivalent to
caffeinate -i) to stop the machine from idle-sleeping so the
WhatsApp/Telegram bridge stays connected. While active, an amber
coffee icon in the titlebar shows the state and can be clicked to
turn it off; a power:caffeinateChanged push keeps the titlebar
indicator and the settings switch in sync.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

apps/x/packages/shared/src/ipc.ts

@@ -1004,6 +1004,20 @@ const ipcSchemas = {
       success: z.literal(true),
     }),
   },
+  // ── Caffeinate (keep system awake, like macOS `caffeinate`) ──
+  'power:getCaffeinate': {
+    req: z.null(),
+    res: z.object({ enabled: z.boolean() }),
+  },
+  'power:setCaffeinate': {
+    req: z.object({ enabled: z.boolean() }),
+    res: z.object({ enabled: z.boolean() }),
+  },
+  // Push: main → renderer when caffeinate state changes, so indicators stay live.
+  'power:caffeinateChanged': {
+    req: z.object({ enabled: z.boolean() }),
+    res: z.null(),
+  },
   // ── Mobile channels (WhatsApp / Telegram bridge) ─────────────
   'channels:getConfig': {
     req: z.null(),