Setting: add member_field_required and update_single_member_field

Add JSONB attribute member_field_required, migration, Change and
Membership code interface for atomic per-field required flag.

lib/membership/setting.ex

@@ -11,6 +11,8 @@ defmodule Mv.Membership.Setting do
   - `club_name` - The name of the association/club (required, cannot be empty)
   - `member_field_visibility` - JSONB map storing visibility configuration for member fields
     (e.g., `%{"street" => false, "house_number" => false}`). Fields not in the map default to `true`.
+  - `member_field_required` - JSONB map storing which member fields are required in forms
+    (e.g., `%{"first_name" => true, "last_name" => true}`). Email is always required; other fields default to optional.
   - `include_joining_cycle` - Whether to include the joining cycle in membership fee generation (default: true)
   - `default_membership_fee_type_id` - Default membership fee type for new members (optional)
 
@@ -42,6 +44,9 @@ defmodule Mv.Membership.Setting do
       # Update member field visibility
       {:ok, updated} = Mv.Membership.update_member_field_visibility(settings, %{"street" => false, "house_number" => false})
 
+      # Update visibility and required for a single member field (e.g. from settings UI)
+      {:ok, updated} = Mv.Membership.update_single_member_field(settings, field: "first_name", show_in_overview: true, required: true)
+
       # Update membership fee settings
       {:ok, updated} = Mv.Membership.update_settings(settings, %{include_joining_cycle: false})
   """
@@ -68,6 +73,7 @@ defmodule Mv.Membership.Setting do
       accept [
         :club_name,
         :member_field_visibility,
+        :member_field_required,
         :include_joining_cycle,
         :default_membership_fee_type_id,
         :vereinfacht_api_url,
@@ -84,6 +90,7 @@ defmodule Mv.Membership.Setting do
       accept [
         :club_name,
         :member_field_visibility,
+        :member_field_required,
         :include_joining_cycle,
         :default_membership_fee_type_id,
         :vereinfacht_api_url,
@@ -109,6 +116,17 @@ defmodule Mv.Membership.Setting do
       change Mv.Membership.Setting.Changes.UpdateSingleMemberFieldVisibility
     end
 
+    update :update_single_member_field do
+      description "Atomically updates visibility and required for a single member field"
+      require_atomic? false
+
+      argument :field, :string, allow_nil?: false
+      argument :show_in_overview, :boolean, allow_nil?: false
+      argument :required, :boolean, allow_nil?: false
+
+      change Mv.Membership.Setting.Changes.UpdateSingleMemberField
+    end
+
     update :update_membership_fee_settings do
       description "Updates the membership fee configuration"
       require_atomic? false
@@ -162,6 +180,44 @@ defmodule Mv.Membership.Setting do
              end,
              on: [:create, :update]
 
+    # Validate member_field_required map structure and content
+    validate fn changeset, _context ->
+               required_config = Ash.Changeset.get_attribute(changeset, :member_field_required)
+
+               if required_config && is_map(required_config) do
+                 invalid_values =
+                   Enum.filter(required_config, fn {_key, value} ->
+                     not is_boolean(value)
+                   end)
+
+                 valid_field_strings = Mv.Constants.member_fields() |> Enum.map(&Atom.to_string/1)
+
+                 invalid_keys =
+                   Enum.filter(required_config, fn {key, _value} ->
+                     key not in valid_field_strings
+                   end)
+                   |> Enum.map(fn {key, _value} -> key end)
+
+                 cond do
+                   not Enum.empty?(invalid_values) ->
+                     {:error,
+                      field: :member_field_required,
+                      message: "All values in member_field_required must be booleans"}
+
+                   not Enum.empty?(invalid_keys) ->
+                     {:error,
+                      field: :member_field_required,
+                      message: "Invalid member field keys: #{inspect(invalid_keys)}"}
+
+                   true ->
+                     :ok
+                 end
+               else
+                 :ok
+               end
+             end,
+             on: [:create, :update]
+
     # Validate default_membership_fee_type_id exists if set
     validate fn changeset, context ->
                fee_type_id =
@@ -219,6 +275,12 @@ defmodule Mv.Membership.Setting do
       description:
         "Configuration for member field visibility in overview (JSONB map). Keys are member field names (atoms), values are booleans."
 
+    attribute :member_field_required, :map,
+      allow_nil?: true,
+      public?: true,
+      description:
+        "Configuration for which member fields are required in forms (JSONB map). Keys are member field names (strings), values are booleans. Email is always required."
+
     # Membership fee settings
     attribute :include_joining_cycle, :boolean do
       allow_nil? false