Kiosk: show all user-visible times as 12-hour AM/PM

Add datetime::formatHm12h/formatTime12h and use them for the Home footer
clock, the Timezone page's local-time sample, and the log viewer
timestamps. Storage and parsing remain 24-hour HH:MM. Extends the
date-format tests with the midnight/noon edge cases.

src/timezone_page.cpp

@@ -1,5 +1,6 @@
 #include "timezone_page.h"
 #include "app_state.h"
+#include "date_format.h"
 #include "logical_size.h"
 #include <SDL3/SDL.h>
 #include <algorithm>
@@ -237,7 +238,13 @@ void TimeZonePage::render(SDL_Renderer* renderer) {
     }
 
     time_t now = std::time(nullptr);
-    std::string localSample = "Local Time: " + radiantwave::timezone::formatUtcToTimezone(now, currentTzCode_);
+    // Show the configured zone's wall-clock time with an AM/PM label; storage
+    // and the rest of the app stay 24-hour.
+    std::string localSample = "Local Time: " +
+        radiantwave::timezone::formatUtcToTimezone(now, currentTzCode_, "%Y-%m-%d") + " " +
+        radiantwave::datetime::formatHm12h(
+            radiantwave::timezone::formatUtcToTimezone(now, currentTzCode_, "%H:%M")) +
+        " " + radiantwave::timezone::formatUtcToTimezone(now, currentTzCode_, "%Z");
     sampleText_.ensure(renderer, fontHeader_, localSample, green);
     if (sampleText_.texture) {
         SDL_FRect dst{700.0f, currentY, sampleText_.width, sampleText_.height};