feat(app): font-atlas rebuild hook + clock/emoji sync

- requestFontRebuild() + preFrame handling so toggling color emoji swaps the atlas live;
  request a rebuild at startup when the saved setting wants color.
- preFrame syncs Typography's color-emoji flag and the util clock flag from settings.
- Chat 0-conf fast-scan cadence now reads the user's poll-rate setting (was a hardcoded 2.5s).

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

src/app.cpp

@@ -293,6 +293,9 @@ bool App::init()
     if (!settings_->load()) {
         DEBUG_LOGF("Warning: Could not load settings, using defaults\n");
     }
+    // The initial font atlas is built (in main, before App renders) with monochrome emoji. If the saved
+    // setting wants color, request a rebuild so the first preFrame switches to the FreeType color atlas.
+    if (settings_->getChatEmojiColor()) font_rebuild_requested_ = true;
     // On upgrade (version mismatch), re-save to persist new defaults + current version
     if (settings_->needsUpgradeSave()) {
         DEBUG_LOGF("[INFO] Wallet upgraded — re-saving settings with new defaults\n");
@@ -532,6 +535,21 @@ void App::preFrame()
         DEBUG_LOGF("App: Font atlas rebuilt after user font-scale change (%.1fx)\n",
                    ui::Layout::userFontScale());
     }
+
+    // Keep Typography's emoji-style flag in sync with the setting so any reload (font-scale, DPI, or the
+    // explicit request below) picks up the right emoji font. Inert unless this is a FreeType build.
+    if (settings_) ui::material::Typography::instance().setColorEmoji(settings_->getChatEmojiColor());
+
+    // App-wide clock format (24h/12h) — drives every user-facing timestamp via util::formatClock*.
+    if (settings_) util::setClock12h(settings_->getTimeFormat() == 1);
+
+    // Explicit rebuild request (e.g. the chat color-emoji toggle) — reload picks up the new emoji style.
+    if (font_rebuild_requested_) {
+        font_rebuild_requested_ = false;
+        auto& typo = ui::material::Typography::instance();
+        typo.reload(io, typo.getDpiScale());
+        DEBUG_LOGF("App: Font atlas rebuilt on request (chat emoji style)\n");
+    }
 }
 
 namespace {
@@ -1174,7 +1192,8 @@ void App::update()
             // normal harvest only re-scans on a new block. Self-gated (no-op without a chat identity /
             // connection / on lite); the in-flight guard keeps overlapping RPCs from stacking.
             chat_fast_scan_accum_ += ImGui::GetIO().DeltaTime;
-            if (chat_fast_scan_accum_ >= 2.5f) {
+            const float chatPoll = settings_ ? settings_->getChatPollRateSec() : 2.5f;  // user-configurable
+            if (chat_fast_scan_accum_ >= chatPoll) {
                 chat_fast_scan_accum_ = 0.0f;
                 fastScanChatMemos();
             }

src/app.h

@@ -171,6 +171,9 @@ public:
     daemon::EmbeddedDaemon* consoleDaemon();
     daemon::XmrigManager* consoleXmrig();
     config::Settings* settings() { return settings_.get(); }
+    // Request a font-atlas rebuild before the next frame (e.g. after toggling color emoji). Handled in
+    // preFrame() via Typography::reload — safe to call from UI code mid-frame.
+    void requestFontRebuild() { font_rebuild_requested_ = true; }
     // Lite wallet controller (non-null only in lite builds with a linked backend).
     wallet::LiteWalletController* liteWallet() { return lite_wallet_.get(); }
     // HushChat service (identity + in-memory message store); the Chat tab reads its store.
@@ -736,6 +739,7 @@ private:
     void fastScanChatMemos();
     bool chat_fast_scan_in_flight_ = false;   // guard against overlapping fast-scan RPCs
     float chat_fast_scan_accum_ = 0.0f;       // seconds since the last fast-scan (dedicated ~2.5s poll)
+    bool font_rebuild_requested_ = false;     // set by requestFontRebuild(); consumed in preFrame()
     // Lite first-run welcome prompt: dismissed for the session once the user picks an action.
     bool lite_firstrun_dismissed_ = false;
     // Lite send-time unlock: set to show the unlock modal when a spend is attempted while locked.