Core: Improve annotations as a collaboration feature

### Workbench affected?

None

### Problem description

I consider this part of #25681.

This is a request for an improved feature that allows users to place annotations in specific parts of the 3D model to comment on the 3D model. This should be seen in the context of for example the [Lens server](https://github.com/FreeCAD/Ondsel-Server).

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

```shell
OS: Arch Linux (tty)
Architecture: x86_64
Version: 1.2.0dev.44440 (Git)
Build date: 2025/11/25 10:47:05
Build type: Unknown
Branch: main
Hash: 972ade948c41f789798bd49a9fa3945e7aa6e4a1
Python 3.13.7, Qt 6.10.0, Coin 4.0.5, Vtk 9.5.2, boost 1_89, Eigen3 5.0.1, PySide 6.10.0
shiboken 6.10.0, SMESH 7.7.1.0, xerces-c 3.3.0, OCC 7.9.2
Locale: English/United States (en_US)
Navigation Style/Orbit Style/Rotation Mode: CAD/Trackball/Drag at cursor
Stylesheet/Theme/QtStyle: OpenDark.qss/OpenDark/
Logical DPI/Physical DPI/Pixel Ratio: 96/92.6073/1.33333
Installed mods:
* OpenTheme 2024.5.16
* fasteners 0.5.34
* WebTools 1.0.0
* osh-autodoc-workbench 0.2.3
* DynamicData 2.70.0
* Curves 0.6.61
* freecad.gears 1.3.0
* sheetmetal 0.7.24
* Ondsel-Lens 2025.11.21.01
```

The issue names no files, tests, or entry points; start by reading #25681 and the linked Lens server context to establish the intended scope. The work is complete when users can place annotations on specific parts of a 3D model and use them as comments, but the issue does not define the interaction or acceptance details.

Written by the indexing model from the issue text.