sar3d: GPU port of the notebook with four views

The sar3d processor is rewritten as a checked port of Multi_antenna_3D_clean_v1.ipynb:
NVRTC kernels, timing from the trace stamps, notebook parameter names and one cubic
SAR_VOXEL_M. It adds front, side, top and 3D views, drops gpr_cpp and the parity tools,
and the GUI speed now applies only while the socket speed is ignored.

python_app/tests/test_socket_speed_controls.py

@@ -0,0 +1,65 @@
+"""Speed authority between a locator socket client and the GUI field.
+
+The data_processor uses the speed a socket client streams unless the live config
+sets `ignore_socket_speed`; then `gpr_speed_m_s` from the GUI field applies. Each
+GPR-like page (gpr, legacy_gpr, sar3d) has its own checkbox and field, and the
+field is editable only while it is the one in force.
+"""
+
+from __future__ import annotations
+
+import os
+import unittest
+from pathlib import Path
+
+os.environ.setdefault("QT_QPA_PLATFORM", "offscreen")
+from PyQt6.QtWidgets import QApplication  # noqa: E402
+
+from python_app.gui.app_window import AppWindow  # noqa: E402
+
+_app: QApplication | None = None
+_window: AppWindow | None = None
+
+# mode -> (checkbox, speed field) attributes of its page
+_PAGES = {
+    "gpr": ("_gpr_ignore_socket_speed_enabled", "_gpr_speed_m_s"),
+    "legacy_gpr": ("_legacy_gpr_ignore_socket_speed_enabled", "_legacy_gpr_speed_m_s"),
+    "sar3d": ("_sar3d_ignore_socket_speed_enabled", "_sar3d_speed_m_s"),
+}
+
+
+def setUpModule() -> None:
+    global _app, _window
+    _app = QApplication.instance() or QApplication([])
+    _window = AppWindow(Path("."))
+
+
+def tearDownModule() -> None:
+    if _window is not None:
+        _window.close()
+
+
+class SocketSpeedControlsTest(unittest.TestCase):
+    def test_speed_field_is_editable_only_while_the_socket_is_ignored(self) -> None:
+        assert _window is not None
+        for mode, (checkbox_name, speed_name) in _PAGES.items():
+            checkbox, speed = getattr(_window, checkbox_name), getattr(_window, speed_name)
+            for ignore in (True, False):
+                checkbox.setChecked(ignore)
+                self.assertEqual(speed.isEnabled(), ignore, msg=f"{mode}, ignore={ignore}")
+
+    def test_live_config_takes_the_active_page(self) -> None:
+        assert _window is not None
+        for mode, (checkbox_name, speed_name) in _PAGES.items():
+            _window._set_combo_current_text(_window._processing_mode, mode)
+            getattr(_window, checkbox_name).setChecked(True)
+            getattr(_window, speed_name).setValue(1.25)
+            config = _window._live_processing_config()
+            self.assertTrue(config.ignore_socket_speed, msg=mode)
+            self.assertAlmostEqual(config.gpr_speed_m_s, 1.25, msg=mode)
+            getattr(_window, checkbox_name).setChecked(False)
+            self.assertFalse(_window._live_processing_config().ignore_socket_speed, msg=mode)
+
+
+if __name__ == "__main__":
+    unittest.main()