More gracefully fail on `pyproject.toml` error

Personne n'a encore pris cette issue.

tried going through the "create environment..." flow with a `pyproject.toml` file but I had an error since my `pyproject.toml` file was incorrectly formatted. Would be good if the error message was better or it failed more gracefully

```
Resolved Python Environment /Users/eleanorboyd/python-envs-scenarios/existing-env-folder/.venv/bin/python
2025-05-14 09:19:39.308 [info] Running: uv pip install --python /Users/eleanorboyd/python-envs-scenarios/existing-env-folder/.venv/bin/python -e /Users/eleanorboyd/python-envs-scenarios/existing-env-folder
2025-05-14 09:19:39.378 [info] error: Failed to extract static metadata from `pyproject.toml`
Caused by: TOML parse error at line 6, column 8
|
6 | name = "existing env folder"
| ^^^^^^^^^^^^^^^^^^^^^
Not a valid package or extra name: "existing env folder". Names must start and end with a letter or digit and may only contain -, _, ., and alphanumeric characters.

```

Commencez par le flux « create environment... » et l’invocation journalisée `uv pip install --python ... -e ...`, en utilisant l’exemple de `pyproject.toml` malformé pour reproduire l’échec. C’est terminé lorsque le flux signale plus clairement l’erreur de métadonnées du paquet ou se termine correctement au lieu d’exposer l’échec brut.

Rédigé par le modèle d'indexation à partir du texte de l'issue.