port C++ UI from broken: ready/splash, ClearPilot menu, onroad widgets, nightrider

Wholesale port of the 10 UI files (main.cc, ui.{cc,h}, onroad.{cc,h},
home.{cc,h}, window.{cc,h}, ready.{cc,h}, SConscript). sidebar.{cc,h}
unchanged.

Brings in:
- splash/ready screen rendered via Qt directly (replaces stock home)
- ready page shown when started but gear=park
- ClearPilot offroad menu (Home/Dashcam/Debug panels) replacing stock
- onroad UI: speed widget reading ClearpilotSpeedDisplay (gpsLocation
  via speed_logicd), speed-limit widget, cruise-vs-limit warning sign
- nightrider mode: camera suppressed, lane lines/path drawn as 2px
  outlines only (ScreenDisplayMode 1 or 4)
- screen power: ScreenDisplayMode 3 forces setAwake(false)
- ignition off blanks screen immediately (tap still wakes)
- Qt-based RPC widget-tree dump server at ipc:///tmp/clearpilot_ui_rpc
- crash handler in main.cc with stack trace

Deviation from broken (3 sites): no_lat_lane_change is read from
paramsMemory (controlsd writes it there in baseline) instead of broken's
custom cereal field frogpilotCarControl.noLatLaneChange. Keeps the
existing self-driving wiring intact.

SConscript drops screenrecorder.cc from qt_src (broken did the same;
omx_encoder.cc still built for dashcamd's future link).

Build clean. UI hasn't been launched yet — that comes after the
controlsd button-handler commit lands.

Translation .ts files are auto-regenerated by Qt's lupdate; included.

selfdrive/ui/main.cc

@@ -1,4 +1,9 @@
 #include <sys/resource.h>
+#include <csignal>
+#include <cstdio>
+#include <cstdlib>
+#include <execinfo.h>
+#include <unistd.h>
 
 #include <QApplication>
 #include <QTranslator>
@@ -8,7 +13,27 @@
 #include "selfdrive/ui/qt/util.h"
 #include "selfdrive/ui/qt/window.h"
 
+// CLEARPILOT: crash handler — prints stack trace to stderr on SIGSEGV/SIGABRT
+static void crash_handler(int sig) {
+  const char *sig_name = (sig == SIGSEGV) ? "SIGSEGV" : (sig == SIGABRT) ? "SIGABRT" : "SIGNAL";
+  fprintf(stderr, "\n=== CRASH: %s (signal %d) ===\n", sig_name, sig);
+
+  void *frames[64];
+  int count = backtrace(frames, 64);
+  fprintf(stderr, "Backtrace (%d frames):\n", count);
+  backtrace_symbols_fd(frames, count, STDERR_FILENO);
+  fprintf(stderr, "=== END CRASH ===\n");
+  fflush(stderr);
+
+  // Re-raise to get default behavior (core dump / exit)
+  signal(sig, SIG_DFL);
+  raise(sig);
+}
+
 int main(int argc, char *argv[]) {
+  signal(SIGSEGV, crash_handler);
+  signal(SIGABRT, crash_handler);
+
   setpriority(PRIO_PROCESS, 0, -20);
 
   qInstallMessageHandler(swagLogMessageHandler);