touch: only offer Power off where something can wake the device (#310)

wb6zsu found the T-Display P4 freezes on Home > Cmdr > Control > Power > Power
off, recoverable only with the hardware switch, under a toast telling him to
click a trackball the board does not have.

Both halves are the same bug. The wake source is armed inside `#if
defined(PIN_USER_BTN)`, which platformio.ini sets per env and the two ESP32-P4
targets never see, so the P4 ran esp_deep_sleep_start() with no wake source
configured: the device is off and nothing short of the switch brings it back.
That is not a freeze, but it is indistinguishable from one.

The Power-off row was gated on `!HAS_THINKNODE_M9` instead -- a board name
standing in for "has a wakeable button", correct for the one board it was
written against and silently wrong for every board added since. It now follows
PIN_USER_BTN, the same symbol that arms the wake, so the row exists exactly when
it can be undone: the M9, the P4 and the Tanmatsu drop it, and any future board
gets the right answer without anyone remembering this.

The toast names the control the board actually has rather than assuming a
trackball.

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

src/ui-touch/UITask.cpp

@@ -39121,7 +39121,12 @@ static void powerRebootCb(lv_event_t* e) {
   g_lv.task->showAlert(TR("Rebooting\xE2\x80\xA6"), 600);
   g_lv.task->rebootDevice();   // flushes chat history, then reboots
 }
-#if !defined(HAS_THINKNODE_M9)   // M9 has no Power-off row (no wake-capable button — see openPowerMenu)
+// Gated on PIN_USER_BTN, which is exactly what arms the deep-sleep wake below.
+// A power-off nobody can undo is not a power-off, it is a brick until the user
+// finds the hardware switch — and that is what the T-Display P4 did: no wake
+// source armed at all, under a toast promising a trackball it does not have
+// (#310). Boards without the symbol get no Power-off row (see openPowerMenu).
+#if defined(PIN_USER_BTN)
 static void powerOffCb(lv_event_t* e) {
   if (lv_event_get_code(e) != LV_EVENT_CLICKED) return;
   closePowerMenu();
@@ -39134,10 +39139,12 @@ static void powerOffCb(lv_event_t* e) {
     the_mesh.flushContactsIfDirty();       // and any coalesced contacts refresh
     the_mesh.persistSyncHistoryNow();      // and the app-sync replay ring (RAM is lost in deep sleep)
     touchPrefsFlush();                     // and all queued A/B preference snapshots
-#if defined(HELTEC_LORA_V4_R8)
-    g_lv.task->showAlert(TR("Powering off\xE2\x80\xA6 press BOOT to wake"), 1500);
-#else
+    // Name the control this board actually has. "Click trackball" was shown on
+    // every board that reached here, trackball or not.
+#if defined(HAS_TDECK_GT911)
     g_lv.task->showAlert(TR("Powering off\xE2\x80\xA6 click trackball to wake"), 1500);
+#else
+    g_lv.task->showAlert(TR("Powering off\xE2\x80\xA6 press BOOT to wake"), 1500);
 #endif
   }
   // Let the toast paint, then enter deep sleep.
@@ -39179,7 +39186,7 @@ static void powerOffCb(lv_event_t* e) {
   esp_deep_sleep_start();   // never returns; a press wakes via full reboot
 #endif
 }
-#endif  // !HAS_THINKNODE_M9 (powerOffCb)
+#endif  // PIN_USER_BTN (powerOffCb)
 
 #if defined(ESP32)
 #if !defined(HAS_TANMATSU) && !defined(HAS_TDISPLAY_P4)
@@ -39280,11 +39287,12 @@ static void openPowerMenu() {
     lv_obj_center(l);
     return b;
   };
-#if defined(HAS_THINKNODE_M9)
-  // No "Power off" here: deep sleep would arm ext0 wake on a user button this
-  // board doesn't have (only a power-cut slider and reset, neither a wakeable
-  // GPIO) — an off state recoverable only by cycling the slider. The slider IS
-  // the power-off. Remaining rows shift up one slot.
+#if !defined(PIN_USER_BTN)
+  // No "Power off" here: nothing on this board can wake it from deep sleep.
+  // The M9 has a power-cut slider and reset, neither a wakeable GPIO; the
+  // T-Display P4 and Tanmatsu have no user button either. On those the physical
+  // switch IS the power-off, and offering a software one that cannot be undone
+  // reads as a freeze (#310). Remaining rows shift up one slot.
   const int p_y = p_y0;
 #else
   mk(TR(LV_SYMBOL_POWER "  Power off"),        powerOffCb,      0xC44B55, p_y0);