feat(util): app-wide 24h/12h clock format

Add util::formatClockDateTime/formatClockTime driven by a process-wide flag (setClock12h,
synced from the time_format setting each frame). Switch the primary user-facing timestamp
displays to it — the transaction list, wallet-state tx + banned-peer times, the explorer
block time, and the block-info dialog — so one preference drives every clock.

Log files, export filenames/content, console line prefixes, the market chart axis, and the
worker-thread "last updated" string intentionally stay fixed 24h.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/data/wallet_state.cpp

@@ -3,6 +3,7 @@
 // Released under the GPLv3
 
 #include "wallet_state.h"
+#include "../util/text_format.h"   // util::formatClockDateTime (app-wide 24h/12h clock)
 #include <algorithm>
 #include <ctime>
 #include <sstream>
@@ -44,13 +45,7 @@ int bestSpendableAddressIndex(const std::vector<AddressInfo>& addresses)
 std::string TransactionInfo::getTimeString() const
 {
     if (timestamp == 0) return "Unknown";
-    
-    std::time_t t = static_cast<std::time_t>(timestamp);
-    std::tm* tm = std::localtime(&t);
-    
-    std::stringstream ss;
-    ss << std::put_time(tm, "%Y-%m-%d %H:%M");
-    return ss.str();
+    return util::formatClockDateTime(timestamp);
 }
 
 std::string TransactionInfo::getTypeDisplay() const
@@ -77,13 +72,7 @@ std::string PeerInfo::getConnectionTime() const
 std::string BannedPeer::getBannedUntilString() const
 {
     if (banned_until == 0) return "Never";
-    
-    std::time_t t = static_cast<std::time_t>(banned_until);
-    std::tm* tm = std::localtime(&t);
-    
-    std::stringstream ss;
-    ss << std::put_time(tm, "%Y-%m-%d %H:%M");
-    return ss.str();
+    return util::formatClockDateTime(banned_until);
 }
 
 } // namespace dragonx

src/ui/windows/block_info_dialog.cpp

@@ -203,10 +203,7 @@ void BlockInfoDialog::render(App* app)
             ImGui::Text("%s", TR("block_timestamp"));
             ImGui::SameLine(lbl.position);
             if (s_block_time > 0) {
-                std::time_t t = static_cast<std::time_t>(s_block_time);
-                char time_buf[64];
-                std::strftime(time_buf, sizeof(time_buf), "%Y-%m-%d %H:%M:%S", std::localtime(&t));
-                ImGui::Text("%s", time_buf);
+                ImGui::Text("%s", dragonx::util::formatClockDateTime(s_block_time, /*withSeconds=*/true).c_str());
             } else {
                 ImGui::TextDisabled("%s", TR("unknown"));
             }

src/ui/windows/explorer_tab.cpp

@@ -1127,10 +1127,8 @@ static void renderBlockDetailModal(App* app) {
         // Row 1: Timestamp | Confirmations
         drawLabelValue(dl, gx, gy, labelW, TR("block_timestamp"), "", capFont, sub1);
         if (s_detail_time > 0) {
-            std::time_t t = static_cast<std::time_t>(s_detail_time);
-            char time_buf[64];
-            std::strftime(time_buf, sizeof(time_buf), "%Y-%m-%d %H:%M:%S", std::localtime(&t));
-            dl->AddText(sub1, sub1->LegacySize, ImVec2(gx + labelW, gy), OnSurface(), time_buf);
+            const std::string tstr = dragonx::util::formatClockDateTime(s_detail_time, /*withSeconds=*/true);
+            dl->AddText(sub1, sub1->LegacySize, ImVec2(gx + labelW, gy), OnSurface(), tstr.c_str());
         }
         dl->AddText(capFont, capFont->LegacySize, ImVec2(gx + halfW, gy), OnSurfaceMedium(), TR("confirmations"));
         snprintf(buf, sizeof(buf), "%d", s_detail_confirmations);

src/ui/windows/transactions_tab.cpp

@@ -64,10 +64,7 @@ struct DisplayTx {
 
 std::string DisplayTx::getTimeString() const {
     if (timestamp <= 0) return TR("pending");
-    std::time_t t = static_cast<std::time_t>(timestamp);
-    char buf[64];
-    std::strftime(buf, sizeof(buf), "%Y-%m-%d %H:%M", std::localtime(&t));
-    return buf;
+    return dragonx::util::formatClockDateTime(timestamp);   // honors the app-wide 24h/12h clock
 }
 
 // Relative time string (localized long form, e.g. "5 minutes ago")

src/util/text_format.cpp

@@ -19,8 +19,38 @@ std::int64_t secondsAgo(std::int64_t timestamp)
     std::int64_t diff = now - timestamp;
     return diff < 0 ? 0 : diff;
 }
+bool g_clock12h = false;   // app-wide 12-hour clock preference (synced from settings each frame)
 } // namespace
 
+void setClock12h(bool enabled) { g_clock12h = enabled; }
+bool clock12h() { return g_clock12h; }
+
+std::string formatClockDateTime(std::int64_t timestamp, bool withSeconds)
+{
+    if (timestamp <= 0) return {};
+    std::time_t t = static_cast<std::time_t>(timestamp);
+    std::tm* tm = std::localtime(&t);   // UI thread only
+    if (!tm) return {};
+    const char* fmt = g_clock12h
+        ? (withSeconds ? "%Y-%m-%d %I:%M:%S %p" : "%Y-%m-%d %I:%M %p")
+        : (withSeconds ? "%Y-%m-%d %H:%M:%S"    : "%Y-%m-%d %H:%M");
+    char buf[40];
+    return std::strftime(buf, sizeof(buf), fmt, tm) > 0 ? std::string(buf) : std::string();
+}
+
+std::string formatClockTime(std::int64_t timestamp, bool withSeconds)
+{
+    if (timestamp <= 0) return {};
+    std::time_t t = static_cast<std::time_t>(timestamp);
+    std::tm* tm = std::localtime(&t);   // UI thread only
+    if (!tm) return {};
+    const char* fmt = g_clock12h
+        ? (withSeconds ? "%I:%M:%S %p" : "%I:%M %p")
+        : (withSeconds ? "%H:%M:%S"    : "%H:%M");
+    char buf[24];
+    return std::strftime(buf, sizeof(buf), fmt, tm) > 0 ? std::string(buf) : std::string();
+}
+
 std::string formatTimeAgo(std::int64_t timestamp)
 {
     if (timestamp <= 0) return {};

src/util/text_format.h

@@ -14,6 +14,19 @@
 namespace dragonx {
 namespace util {
 
+// App-wide clock format (24-hour vs 12-hour). Set once per frame by the App from the global
+// `time_format` setting (setClock12h); the formatters below read it so a single preference drives
+// every user-facing timestamp. The Chat tab resolves its own override separately.
+void setClock12h(bool enabled);
+bool clock12h();
+
+// Format an epoch timestamp as a local wall-clock date+time honoring the app clock setting:
+//   24h -> "YYYY-MM-DD HH:MM[:SS]",  12h -> "YYYY-MM-DD hh:MM[:SS] AM/PM". Empty when ts <= 0.
+std::string formatClockDateTime(std::int64_t timestamp, bool withSeconds = false);
+
+// Just the time-of-day portion honoring the clock setting: 24h "HH:MM[:SS]" / 12h "hh:MM[:SS] AM/PM".
+std::string formatClockTime(std::int64_t timestamp, bool withSeconds = false);
+
 // Localized relative time, e.g. "5 minutes ago" (via i18n). Empty when timestamp <= 0.
 std::string formatTimeAgo(std::int64_t timestamp);