reset to pre-modification baseline; restart feature work from clean state

Restoring the working tree to the pristine pre-Claude baseline previously
preserved at /data/clearpilot (now /data/clearpilot-baseline). The prior
modified-but-broken tree is snapshotted at /data/openpilot-broken-2026-05-03
and tagged here as pre-reset-2026-05-03 for reference.

From here, features (UI changes, dashcam, telemetry, GPS, display modes,
speed logic, standstill power saving, etc.) will be re-introduced one at
a time with proper testing.

selfdrive/ui/main.cc

@@ -1,9 +1,4 @@
 #include <sys/resource.h>
-#include <csignal>
-#include <cstdio>
-#include <cstdlib>
-#include <execinfo.h>
-#include <unistd.h>
 
 #include <QApplication>
 #include <QTranslator>
@@ -13,27 +8,7 @@
 #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);