Add the management app: club-facing UI + real fee-payment tracking

Gives clubs a self-service /manage/ area for members, families, teams,
roles, and season memberships, alongside real fee-payment tracking
(FeePayment, record_payment/mark_as_paid/remaining_balance) so a
membership's paid status reflects actual money received instead of a
single manually-set flag.

members/services/family.py

@@ -0,0 +1,122 @@
+"""Registering families: a parent (who needs a login) and a child (who doesn't),
+linked to each other -- either together as a new family, or one at a time onto an
+existing one.
+"""
+
+from django.contrib.auth import get_user_model
+from django.db import transaction
+from django.utils import timezone
+
+from club.models import ClubMembership
+from members.models import Family, FamilyMembership, Member
+
+User = get_user_model()
+
+
+def find_member_by_email(email):
+    """The Member behind a login email, if that account exists at all."""
+    return Member.objects.filter(user__email__iexact=email).first()
+
+
+def get_or_create_login_member(email, first_name="", last_name=""):
+    """Find or create the Member behind ``email``, creating a User (no usable
+    password -- they set one via the reset-link flow) the first time we see them.
+    Mirrors controlpanel.services.admins.grant_club_admin.
+    """
+    email = email.lower()
+    user, user_created = User.objects.get_or_create(email=email, defaults={"is_active": True})
+    if user_created:
+        user.set_unusable_password()
+        user.save(update_fields=["password"])
+
+    member, _ = Member.objects.get_or_create(user=user, defaults={"first_name": first_name, "last_name": last_name})
+    return member
+
+
+def grant_login(member, email):
+    """Give a login-less member (a child old enough to need their own account, most
+    often) the ability to sign in -- a new User with no usable password, same as
+    get_or_create_login_member; they set one via the reset-link flow. Unlike that
+    function, this attaches the login to a specific, already-existing Member rather
+    than finding-or-creating one -- the caller's form has already checked the email
+    isn't already in use."""
+    user = User.objects.create(email=email.lower(), is_active=True)
+    user.set_unusable_password()
+    user.save(update_fields=["password"])
+
+    member.user = user
+    member.save(update_fields=["user"])
+    return user
+
+
+def _enrol(club, season, member):
+    """Sign a member up for the club's current season, if there is one. The
+    implicit MEMBER role follows automatically (club/signals.py)."""
+    if season is None:
+        return None
+
+    membership, _ = ClubMembership.objects.get_or_create(
+        club=club,
+        member=member,
+        season=season,
+        defaults={"status": ClubMembership.StatusChoices.ACTIVE, "signed_up_at": timezone.localdate()},
+    )
+    return membership
+
+
+@transaction.atomic
+def register_family(club, season, *, parent_email, parent_first_name, parent_last_name, child_first_name, child_last_name, child_date_of_birth=None):
+    """Create a new family in one go: a parent (with a login) and a child
+    (without one), linked to each other and signed up for ``season``."""
+    parent = get_or_create_login_member(parent_email, parent_first_name, parent_last_name)
+    child = Member.objects.create(first_name=child_first_name, last_name=child_last_name, date_of_birth=child_date_of_birth)
+
+    family = Family.objects.create()
+    FamilyMembership.objects.create(family=family, member=parent, role=FamilyMembership.FamilyRole.PARENT)
+    FamilyMembership.objects.create(family=family, member=child, role=FamilyMembership.FamilyRole.CHILD)
+
+    _enrol(club, season, parent)
+    _enrol(club, season, child)
+
+    return family
+
+
+@transaction.atomic
+def add_child_to_family(club, season, family, *, first_name, last_name, date_of_birth=None):
+    """A family that needs one more child registered -- a sibling joining, most often."""
+    child = Member.objects.create(first_name=first_name, last_name=last_name, date_of_birth=date_of_birth)
+    FamilyMembership.objects.create(family=family, member=child, role=FamilyMembership.FamilyRole.CHILD)
+    _enrol(club, season, child)
+
+    return child
+
+
+@transaction.atomic
+def add_parent_to_family(club, season, family, *, email, first_name="", last_name=""):
+    """A family that needs one more parent/guardian registered."""
+    parent = get_or_create_login_member(email, first_name, last_name)
+    # get_or_create, not create: re-adding an email already on this family (a typo'd
+    # re-submit, say) must not trip unique_member_per_family.
+    FamilyMembership.objects.get_or_create(family=family, member=parent, defaults={"role": FamilyMembership.FamilyRole.PARENT})
+    _enrol(club, season, parent)
+
+    return parent
+
+
+def attach_to_family(member, *, role, family=None):
+    """Link a standalone member into a family -- a new one, or an existing one they
+    turn out to belong to (e.g. a second parent already registered separately)."""
+    if family is None:
+        family = Family.objects.create()
+
+    FamilyMembership.objects.get_or_create(family=family, member=member, defaults={"role": role})
+    return family
+
+
+@transaction.atomic
+def detach_from_family(member, family):
+    """Remove member from one specific family -- they may still belong to others.
+    An empty family (this was its last member) is cleaned up same as before."""
+    FamilyMembership.objects.filter(member=member, family=family).delete()
+    if not family.memberships.exists():
+        family.delete()