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/windows/mining_tab.cpp

@@ -1297,10 +1297,28 @@ static void RenderMiningTabContent(App* app)
                     // Status text above bar
                     int ct = s_benchmark.current_index < (int)s_benchmark.candidates.size()
                            ? s_benchmark.candidates[s_benchmark.current_index] : 0;
-                    snprintf(buf, sizeof(buf), "%s %d/%d (%dt)",
-                             TR("mining_benchmark_testing"),
-                             s_benchmark.current_index + 1,
-                             (int)s_benchmark.candidates.size(), ct);
+                    // Estimated remaining time
+                    int remaining_tests = (int)s_benchmark.candidates.size() - s_benchmark.current_index;
+                    float elapsed_in_phase = s_benchmark.phase_timer;
+                    float phase_total = (s_benchmark.phase == ThreadBenchmark::Phase::WarmingUp)
+                                      ? ThreadBenchmark::WARMUP_SECS
+                                      : ThreadBenchmark::MEASURE_SECS;
+                    float remaining_in_current = std::max(0.0f, phase_total - elapsed_in_phase);
+                    // Remaining tests after current each need warmup + measure
+                    float est_secs = remaining_in_current
+                                   + (remaining_tests - 1) * (ThreadBenchmark::WARMUP_SECS + ThreadBenchmark::MEASURE_SECS);
+                    int est_min = (int)(est_secs / 60.0f);
+                    int est_sec = (int)est_secs % 60;
+                    if (est_min > 0)
+                        snprintf(buf, sizeof(buf), "%s %d/%d (%dt) ~%dm%ds",
+                                 TR("mining_benchmark_testing"),
+                                 s_benchmark.current_index + 1,
+                                 (int)s_benchmark.candidates.size(), ct, est_min, est_sec);
+                    else
+                        snprintf(buf, sizeof(buf), "%s %d/%d (%dt) ~%ds",
+                                 TR("mining_benchmark_testing"),
+                                 s_benchmark.current_index + 1,
+                                 (int)s_benchmark.candidates.size(), ct, est_sec);
                     ImVec2 txtSz = capFont->CalcTextSizeA(capFont->LegacySize, FLT_MAX, 0, buf);
                     dl->AddText(capFont, capFont->LegacySize,
                                 ImVec2(barX + (barW - txtSz.x) * 0.5f, barY - txtSz.y - 2.0f * dp),