session logging, build-only mode, park splash, boot logo spinner

- Per-process stderr logging to /data/log2/{session}/ with time-safe
  directory naming (boot-xxx renamed once GPS/NTP sets clock)
- Aggregate session.log with major events (start/stop, transitions)
- 30-day log rotation cleanup on manager startup
- build_only.sh: compile without starting manager, non-blocking error
  display, kills stale processes
- build.py: copies updated spinner binary after successful build
- Onroad park mode: show splash screen when car is on but in park,
  switch to camera view when shifted to drive, honor screen on/off
- Spinner: full-screen boot logo background from /usr/comma/bg.jpg
  with white progress bar overlay
- Boot logo: auto-regenerate when boot_logo.png changes, 140% scale
- launch_openpilot.sh: cd to /data/openpilot for reliable execution
- launch_chffrplus.sh: kill stale text error displays on startup
- spinner shell wrapper: prefer freshly built _spinner over prebuilt

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

selfdrive/ui/qt/spinner.h

@@ -1,36 +1,23 @@
-#include <array>
-
 #include <QLabel>
 #include <QPixmap>
 #include <QProgressBar>
 #include <QSocketNotifier>
-#include <QVariantAnimation>
 #include <QWidget>
 
-constexpr int spinner_fps = 30;
-constexpr QSize spinner_size = QSize(360, 360);
-
-class TrackWidget : public QWidget  {
-  Q_OBJECT
-public:
-  TrackWidget(QWidget *parent = nullptr);
-
-private:
-  void paintEvent(QPaintEvent *event) override;
-  std::array<QPixmap, spinner_fps> track_imgs;
-  QVariantAnimation m_anim;
-};
-
 class Spinner : public QWidget {
   Q_OBJECT
 
 public:
   explicit Spinner(QWidget *parent = 0);
 
+protected:
+  void paintEvent(QPaintEvent *event) override;
+
 private:
   QLabel *text;
   QProgressBar *progress_bar;
   QSocketNotifier *notifier;
+  QPixmap bg_img;
 
 public slots:
   void update(int n);