Interactively probing data

### User Story Description

As a user, I want to probe interactively the model so I can see the values of variables at specific points.

The probe will display the X,Y,Z position and the value of the variable the part is currently colored by. We will display the nearest data available (no need to interpolate the nearest nodes).
When probing a vector variable, the probe will return the magnitude of the variable.

Here links to UI proposals:

Prototype link: https://www.figma.com/proto/fh0pQYoi8n88rB3Xtx5QGl/Theia-3D-Viewer?page-id=58279%3A20202&node-id=58279-32750&viewport=701%2C268%2C0.24&t=dBfDvEJAtvlEN8mH-1&scaling=min-zoom&content-scaling=fixed&starting-point-node-id=58279%3A32750

Documentation/Slides: https://www.figma.com/slides/K31bZ6YPOhV4JG7jIk6Bzc/Theia-Interactive-Probe-Feature-Doc?node-id=1-42&t=IW44F1Snbz363qJX-0

### Acceptance Criteria

Start a session of VISOR. Load a model. Color a part by a variable.

Probe the part. On the rendering window, the X,Y,Z values and variable values will appear.

Repeat with a vector variable. The probe returns the magnitude of the vector.

Now, make the part with a constant color - no color by variable. Probe a point again. The probe returns X,Y,Z but no variable value.

### Additional Links

_No response_

### Requires new or update to third party ? If "yes" add the name(s) and the version(s) of the Third Party Software.

No

### Name and Version for Third Parties

_No response_

Start with the VISOR rendering window and review the linked Figma prototype and feature documentation to understand the proposed interaction. Verify how a loaded model and its currently colored variable are exposed before implementing the probe behavior. Done means the acceptance criteria pass for scalar, vector, and constant-color parts, including X,Y,Z display and vector magnitude handling.

Written by the indexing model from the issue text.