examples/calculator: use final board setup

Initialize the board through the current final-setup interface.

Assisted-by: OpenAI Codex:gpt-5.6-sol
Signed-off-by: aviralgarg05 <gargaviral99@gmail.com>

Author: aviralgarg05

examples/calculator/calculator_main.c

@@ -36,30 +36,13 @@
 
 #include <system/nxstore_chrome.h>
 
-/****************************************************************************
- * Pre-processor Definitions
- ****************************************************************************/
-
-#undef NEED_BOARDINIT
-
-#if defined(CONFIG_BOARDCTL) && !defined(CONFIG_NSH_ARCHINIT)
-#  define NEED_BOARDINIT 1
-#endif
-
 #define CALC_DISPLAY_MAX 16
 
 /****************************************************************************
  * Private Data
  ****************************************************************************/
 
-/* Set only by quit_signal_handler(), an async-signal-safe flag - the
- * actual shutdown happens from the main loop, a known-safe point,
- * rather than from the handler itself.  See games/NXDoom's
- * i_install_quit_signal()/i_poll_quit_signal() for the same pattern:
- * an external supervisor (nxstore) has no in-app quit path to drive,
- * so it can only ask this process to exit from the outside via
- * SIGTERM.
- */
+/* Polled by the main loop for cooperative shutdown. */
 
 static volatile sig_atomic_t g_quit_requested;
 
@@ -79,15 +62,7 @@ static void quit_signal_handler(int signo)
   g_quit_requested = 1;
 }
 
-/* nxstore's own "Close" bar is confined to the top 36px of the display
- * so it can coexist with full-screen children like this one - a
- * convention that only works if the child app leaves that strip alone.
- * This app's display/keypad fill the entire canvas, so nxstore's bar
- * gets overdrawn as soon as this screen loads.  Give the calculator its
- * own close affordance instead: tapping it just sets the same quit flag
- * SIGTERM does, so nxstore's nxstore_poll_running_app() sees the process
- * exit on its own and returns to the app list automatically.
- */
+/* Let standalone launches exit without an external SIGTERM. */
 
 static void close_event_cb(lv_event_t *e)
 {
@@ -162,9 +137,7 @@ static void calc_handle_digit(char digit)
   len = strlen(g_display_buf);
   if (len + 1 >= sizeof(g_display_buf))
     {
-      /* Display is already at capacity - drop the keypress rather than
-       * overflow g_display_buf or silently truncate mid-number.
-       */
+      /* Ignore digits that do not fit. */
 
       return;
     }
@@ -370,8 +343,8 @@ int main(int argc, FAR char *argv[])
       return -1;
     }
 
-#ifdef NEED_BOARDINIT
-  boardctl(BOARDIOC_INIT, 0);
+#ifdef CONFIG_BOARDCTL_FINALINIT
+  boardctl(BOARDIOC_FINALINIT, 0);
 #endif
 
   lv_init();
@@ -464,9 +437,7 @@ int main(int argc, FAR char *argv[])
 
           if (row == 4)
             {
-              /* Single wide "=" button spans the whole row - only
-               * instantiate it once, on the first column.
-               */
+              /* Create the full-width button once. */
 
               if (col > 0)
                 {