Use pyproject.toml + uv_build

This replaces setup.py by a modern pyproject.toml using uv_build
backend.

Dependencies are being also managed by uv, so to install dependencies
and run the project one can execute:

```
uv sync
uv run pytest # optional
python -m avp
```

To build the both source and binary (wheel) distribution package run:
```
uv build
```

Uv can be installed with `pip install uv`.

The directory structure has been changed to reflect best practices.
- src/* -> src/avp/
- src/tests -> ../tests

1 files changed, 1 insertions, 1 deletions

diff --git a/src/__main__.py b/src/avp/cli.py
index db48788..02ceee6 100644
--- a/src/__main__.py
+++ b/src/avp/cli.py
@@ -51,7 +51,7 @@ def main() -> int:
     # Both branches here may occur in one execution:
     # Commandline parsing could change mode back to GUI
     if mode == "GUI":
-        from .gui.mainwindow import MainWindow
+        from avp.gui.mainwindow import MainWindow
 
         mainWindow = MainWindow(proj, dpi)
         log.debug("Finished creating MainWindow")