BIM: Sliding door can be placed in corners where opening is physically impossible

### Problem description

Description
Currently, it is possible to place a sliding door (e.g. in BIM/Arch workflows) directly adjacent to a wall corner or perpendicular wall without any validation of clearance for opening.

This results in geometrically valid placement, but physically impossible behavior — the door panel cannot slide/open due to obstruction.

Steps to reproduce

1. Create two perpendicular walls forming a corner
2. Insert a sliding door in one wall
3. Move the sliding door close to the corner (zero or minimal offset)
4. Observe that placement is allowed without any warning or constraint

Expected behavior

* The system should check if there is sufficient clearance for the sliding panel to open
* If the door is too close to a corner or obstruction:
* Either prevent placement
* Or show a warning (e.g. “Insufficient clearance for sliding door opening”)

Actual behavior

* No validation is performed
* Doors can be placed in positions where opening is not possible

Why this matters
This leads to:

* Physically invalid BIM models
* Errors in downstream workflows (construction, clash detection, fabrication)
* Reduced reliability of FreeCAD for architectural design

Suggested improvement

* Add a geometric clearance check along the sliding axis
* Detect nearby walls or obstacles within the opening path
* Optionally visualize the opening envelope for validation

Additional context
This is especially important for BIM workflows where doors must respect real-world constraints and constructability.

### Workbench affected?

None

### Steps to reproduce

Up there is description

### Expected behavior

Must be impossible to open the door in direction of corner and door location must be bigger then door with from corner

### Actual behavior

There is no checking

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

```shell
Freecad 1.2
```

### Last known good version (optional)

```shell

```