v1.2.0: UX audit — security fixes, accessibility, and polish

Security (P0):
- Fix sidebar remaining interactive behind lock screen
- Extend auto-lock idle detection to include active widget interactions
- Distinguish missing PIN vault from wrong PIN; auto-switch to passphrase

Blocking UX (P1):
- Add 15s timeout for encryption state check to prevent indefinite loading
- Show restart reason in loading overlay after wallet encryption
- Add Force Quit button on shutdown screen after 10s
- Warn user if embedded daemon fails to start during wizard completion

Polish (P2):
- Use configured explorer URL in Receive tab instead of hardcoded URL
- Increase request memo buffer from 256 to 512 bytes to match Send tab
- Extend notification duration to 5s for critical operations (tx sent,
  wallet encrypted, key import, backup, export)
- Add Reduce Motion accessibility setting (disables page fade + balance lerp)
- Show estimated remaining time during mining thread benchmark
- Add staleness indicator to market price data (warning after 5 min)

New i18n keys: incorrect_pin, incorrect_passphrase, pin_not_set,
restarting_after_encryption, force_quit, reduce_motion, tt_reduce_motion,
ago, wizard_daemon_start_failed

src/ui/pages/settings_page.cpp

@@ -93,6 +93,9 @@ static bool sp_gradient_background = false;
 // Low-spec mode
 static bool sp_low_spec_mode = false;
 
+// Reduce motion (accessibility)
+static bool sp_reduce_motion = false;
+
 // Font scale (user accessibility, 1.0–3.0)
 static float sp_font_scale = 1.0f;
 
@@ -179,6 +182,7 @@ static void loadSettingsPageState(config::Settings* settings) {
     sp_theme_effects_enabled = settings->getThemeEffectsEnabled();
     sp_low_spec_mode = settings->getLowSpecMode();
     effects::setLowSpecMode(sp_low_spec_mode);
+    sp_reduce_motion = settings->getReduceMotion();
     sp_font_scale = settings->getFontScale();
     Layout::setUserFontScale(sp_font_scale);  // sync with Layout on load
     sp_keep_daemon_running = settings->getKeepDaemonRunning();
@@ -232,6 +236,7 @@ static void saveSettingsPageState(config::Settings* settings) {
     settings->setScanlineEnabled(sp_scanline_enabled);
     settings->setThemeEffectsEnabled(sp_theme_effects_enabled);
     settings->setLowSpecMode(sp_low_spec_mode);
+    settings->setReduceMotion(sp_reduce_motion);
     settings->setFontScale(sp_font_scale);
     settings->setKeepDaemonRunning(sp_keep_daemon_running);
     settings->setStopExternalDaemon(sp_stop_external_daemon);
@@ -672,6 +677,12 @@ void RenderSettingsPage(App* app) {
                 }
                 if (ImGui::IsItemHovered()) ImGui::SetTooltip("%s", TR("tt_simple_bg"));
 
+                ImGui::SameLine(0, Layout::spacingLg());
+                if (ImGui::Checkbox(TrId("reduce_motion", "reduce_motion").c_str(), &sp_reduce_motion)) {
+                    saveSettingsPageState(app->settings());
+                }
+                if (ImGui::IsItemHovered()) ImGui::SetTooltip("%s", TR("tt_reduce_motion"));
+
                 ImGui::BeginDisabled(sp_low_spec_mode);
 
                 ImGui::SameLine(0, Layout::spacingLg());
@@ -962,6 +973,11 @@ void RenderSettingsPage(App* app) {
                 }
                 if (ImGui::IsItemHovered()) ImGui::SetTooltip("%s", TR("tt_simple_bg_alt"));
 
+                if (ImGui::Checkbox(TrId("reduce_motion", "reduce_motion").c_str(), &sp_reduce_motion)) {
+                    saveSettingsPageState(app->settings());
+                }
+                if (ImGui::IsItemHovered()) ImGui::SetTooltip("%s", TR("tt_reduce_motion"));
+
                 ImGui::BeginDisabled(sp_low_spec_mode);
 
                 if (ImGui::Checkbox(TrId("console_scanline", "scanline").c_str(), &sp_scanline_enabled)) {