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/gui/runtime/sar3d_views.py

@@ -1,30 +0,0 @@
-"""Shared mapping for the sar3d bottom-view projection choices.
-
-The bottom plot of the sar3d mode projects the imaged volume along a
-horizontal direction rotated around the vertical Y axis: 0° = front view
-(X horizontal), 90° = side view (Z horizontal). One shared mapping keeps the
-combo box, the live-config build, the profile persistence and the plot labels
-consistent.
-"""
-
-from __future__ import annotations
-
-SAR3D_BOTTOM_VIEW_CHOICES: tuple[tuple[str, float], ...] = (
-    ("front (0°)", 0.0),
-    ("30°", 30.0),
-    ("60°", 60.0),
-    ("side (90°)", 90.0),
-)
-
-
-def sar3d_bottom_view_deg_from_label(label: str) -> float:
-    """Map a bottom-view combo label to its projection angle in degrees."""
-    for choice_label, degrees in SAR3D_BOTTOM_VIEW_CHOICES:
-        if choice_label == label:
-            return degrees
-    return 0.0
-
-
-def sar3d_bottom_view_label_from_deg(degrees: float) -> str:
-    """Map a projection angle to the nearest bottom-view combo label."""
-    return min(SAR3D_BOTTOM_VIEW_CHOICES, key=lambda choice: abs(choice[1] - float(degrees)))[0]