Macro/Scripting: Project-specific Python scripts (local macros)

### Feature description

In FreeCAD, one can write (or use) Macros, either stored in the User's config or system-wide config.
This is very nice for general-purpose macros that can do heavy lifting, but for specialized scripts, not so much.

I have a simple use case: batch exporting a series of Part's bodies and Parts Containers (the yellow box :)) individually, with a name mapping and a single output folder (e.g. "Exports").

Nowadays it's fairly trivial to write a small python script to have an object/name mapping (e.g: "Shaft1" -> "Gearbox.Shaft1.stl") ; but within FreeCAD there is no easy ways to run such a small script via some automation.

You *could* jump in the console and write the same 2 or 3 lines over and over (load script & run essentially ).
You could also write a global User macro, but this won't be valid outside your project's context.

So, albeit there are ways to work around this feature, I think having a local customizable macro stored within a project (or a parent folder we can point to with relative paths), would be very nice :smile:

### Workbench affected?
None / Macro's support maybe ?

### Steps to reproduce

Not really a bug per-se, rather a feature request so I'm intentionally leaving this section blank.

### Expected behavior

Projects can contain a script file in the tree view (either a real file seating next to the .FCStd file or somewhere else on your computer, usually quite close -> pointer/reference to a location).

We can wire a small macro (or even better, automate the export on "Save" hooks !)

### Actual behavior

I have to work around this missing feature and either do the exports manually every time, or jump into the Python console.

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

```shell
OS: Arch Linux (GNOME/gnome/wayland)
Architecture: x86_64
Version: 1.1.1.20260414 (Git shallow) AppImage
Build date: 2026/04/14 22:09:59
Build type: Release
Branch: (HEAD detached at 0108fd4b4)
Hash: 0108fd4b4850cc46e625b60e53cea7a7bbe69f8d
Python 3.11.14, Qt 6.8.3, Coin 4.0.3, Vtk 9.3.1, boost 1_86, Eigen3 3.4.0, PySide 6.8.3
shiboken 6.8.3, xerces-c 3.3.0, IfcOpenShell 0.8.4, OCC 7.8.1
Locale: French/France (fr_FR)
Navigation Style/Orbit Style/Rotation Mode: CAD/Trackball/Drag at cursor
Stylesheet/Theme/QtStyle: FreeCAD.qss/FreeCAD Dark/
Logical DPI/Physical DPI/Pixel Ratio: 96/92.6123/1
Installed mods:
* A2plus 0.4.64
* freecad.gears 1.3.0
```

## Note
Hi moderators/maintainers !
I could not find any template related to FeatureRequests anymore, I apologize if that's not the right place to upload such a ticket.

No files or tests are named. Start by tracing the existing macro support, Python console, and project tree handling, then examine whether save hooks are already exposed. Done means agreeing on a project-local script representation and a clear way to run it from the project context, with behavior covered by appropriate tests.

Written by the indexing model from the issue text.