TechDraw: section selecting and edge in Python does not highlight it

### Problem description

In a Techdraw section, if you select a line by
`Gui.Selection.addSelection('projet','view','EdgeN')`
The edge do appear in the selection but is not visible. Same for a face.
It works for the view, but not for the section

### Workbench affected?

TechDraw

### Steps to reproduce

Just create a project with a cube Cube
Then switch to Techdraw and add a page/view/section
Select a line normally in the section.
Go to Python Console et type the command written when select was done. (Gui.Selection.addSelection...)

### Expected behavior

The line is selected and visible (color change)

### Actual behavior

Le line is selected but not visible

### Development version About Info (in Safe Mode)

```shell
I tried in the last weekly:

OS: Linux Mint 22.3 Cinnamon (X-Cinnamon/cinnamon/xcb)
Architecture: x86_64
Version: 26.3.0dev.20260804 (Git shallow) AppImage
Build date: 2026/08/04 21:26:11
Build type: Release
Branch: (HEAD detached at 80923ab1b)
Hash: 80923ab1be1f31fff0a54db956177d582a658bab
Python 3.11.14, Qt 6.8.3, Coin 4.0.10 (bundled), Pivy 0.6.11 (bundled), Vtk 9.3.1, boost 1_86, Eigen3 3.4.0, PySide 6.8.3
shiboken 6.8.3, xerces-c 3.3.0, Clipper2 , IfcOpenShell 0.8.0, OCC 7.8.1
Locale: French/France (fr_FR)
Stylesheet/Theme/QtStyle: FreeCAD.qss/FreeCAD Light/
QPA/File dialog/Color dialog: xcb/via Qt/via Qt
Navigation Style/Orbit Style/Rotation Mode: Gesture/Rounded Arcball/Window center
Logical DPI/Physical DPI/Pixel Ratio: 96/81.5973/1
OpenGL version/vendor/renderer: 4.6 (Compatibility Profile) Mesa 25.2.8-0ubuntu0.24.04.2/Intel/Mesa Intel(R) Graphics (RKL GT1)
```

### Last known good version (optional)

```shell

```

Start by reproducing the issue with a TechDraw page, view, and section, then run the recorded Gui.Selection.addSelection command in the Python Console. Compare the selection path for a section edge or face with the working view selection; done means the programmatic selection is visibly highlighted with the expected color.

Written by the indexing model from the issue text.