✨(project) Django boilerplate

This commit introduces a boilerplate inspired by https://github.com/numerique-gouv/impress.
The code has been cleaned to remove unnecessary Impress logic and dependencies.

Changes made:
- Removed Minio, WebRTC, and create bucket from the stack.
- Removed the Next.js frontend (it will be replaced by Vite).
- Cleaned up impress-specific backend logics.

The whole stack remains functional:
- All tests pass.
- Linter checks pass.
- Agent Connexion sources are already set-up.

Why clear out the code?

To adhere to the KISS principle, we aim to maintain a minimalist codebase. Cloning Impress
allowed us to quickly inherit its code quality tools and deployment configurations for staging,
pre-production, and production environments.

What’s broken?
- The tsclient is not functional anymore.
- Some make commands need to be fixed.
- Helm sources are outdated.
- Naming across the project sources are inconsistent (impress, visio, etc.)
- CI is not configured properly.

This list might be incomplete. Let's grind it.

src/backend/core/models.py

@@ -0,0 +1,143 @@
+"""
+Declare and configure the models for the impress core application
+"""
+import uuid
+from logging import getLogger
+
+from django.conf import settings
+from django.contrib.auth import models as auth_models
+from django.contrib.auth.base_user import AbstractBaseUser
+from django.core import mail, validators
+from django.db import models
+from django.utils.functional import lazy
+from django.utils.translation import gettext_lazy as _
+
+from timezone_field import TimeZoneField
+
+logger = getLogger(__name__)
+
+
+class BaseModel(models.Model):
+    """
+    Serves as an abstract base model for other models, ensuring that records are validated
+    before saving as Django doesn't do it by default.
+
+    Includes fields common to all models: a UUID primary key and creation/update timestamps.
+    """
+
+    id = models.UUIDField(
+        verbose_name=_("id"),
+        help_text=_("primary key for the record as UUID"),
+        primary_key=True,
+        default=uuid.uuid4,
+        editable=False,
+    )
+    created_at = models.DateTimeField(
+        verbose_name=_("created on"),
+        help_text=_("date and time at which a record was created"),
+        auto_now_add=True,
+        editable=False,
+    )
+    updated_at = models.DateTimeField(
+        verbose_name=_("updated on"),
+        help_text=_("date and time at which a record was last updated"),
+        auto_now=True,
+        editable=False,
+    )
+
+    class Meta:
+        abstract = True
+
+    def save(self, *args, **kwargs):
+        """Call `full_clean` before saving."""
+        self.full_clean()
+        super().save(*args, **kwargs)
+
+
+class User(AbstractBaseUser, BaseModel, auth_models.PermissionsMixin):
+    """User model to work with OIDC only authentication."""
+
+    sub_validator = validators.RegexValidator(
+        regex=r"^[\w.@+-]+\Z",
+        message=_(
+            "Enter a valid sub. This value may contain only letters, "
+            "numbers, and @/./+/-/_ characters."
+        ),
+    )
+
+    sub = models.CharField(
+        _("sub"),
+        help_text=_(
+            "Required. 255 characters or fewer. Letters, numbers, and @/./+/-/_ characters only."
+        ),
+        max_length=255,
+        unique=True,
+        validators=[sub_validator],
+        blank=True,
+        null=True,
+    )
+    email = models.EmailField(_("identity email address"), blank=True, null=True)
+
+    # Unlike the "email" field which stores the email coming from the OIDC token, this field
+    # stores the email used by staff users to login to the admin site
+    admin_email = models.EmailField(
+        _("admin email address"), unique=True, blank=True, null=True
+    )
+
+    language = models.CharField(
+        max_length=10,
+        choices=lazy(lambda: settings.LANGUAGES, tuple)(),
+        default=settings.LANGUAGE_CODE,
+        verbose_name=_("language"),
+        help_text=_("The language in which the user wants to see the interface."),
+    )
+    timezone = TimeZoneField(
+        choices_display="WITH_GMT_OFFSET",
+        use_pytz=False,
+        default=settings.TIME_ZONE,
+        help_text=_("The timezone in which the user wants to see times."),
+    )
+    is_device = models.BooleanField(
+        _("device"),
+        default=False,
+        help_text=_("Whether the user is a device or a real user."),
+    )
+    is_staff = models.BooleanField(
+        _("staff status"),
+        default=False,
+        help_text=_("Whether the user can log into this admin site."),
+    )
+    is_active = models.BooleanField(
+        _("active"),
+        default=True,
+        help_text=_(
+            "Whether this user should be treated as active. "
+            "Unselect this instead of deleting accounts."
+        ),
+    )
+
+    objects = auth_models.UserManager()
+
+    USERNAME_FIELD = "admin_email"
+    REQUIRED_FIELDS = []
+
+    class Meta:
+        db_table = "impress_user"
+        verbose_name = _("user")
+        verbose_name_plural = _("users")
+
+    def __str__(self):
+        return self.email or self.admin_email or str(self.id)
+
+    def email_user(self, subject, message, from_email=None, **kwargs):
+        """Email this user."""
+        if not self.email:
+            raise ValueError("User has no email address.")
+        mail.send_mail(subject, message, from_email, [self.email], **kwargs)
+
+    def get_teams(self):
+        """
+        Get list of teams in which the user is, as a list of strings.
+        Must be cached if retrieved remotely.
+        """
+        return []