test(member-live): keep deadlock-prone member tests synchronous

These member/group/custom-field LiveView tests stay async: false. With the
foreign keys now deferrable the create_member deadlock no longer forces it, so
the rationale is updated: they remain synchronous as a deferred scope decision,
and index_groups_url_params/member_filter_component additionally have separate
async-isolation issues that must be fixed before they can run in parallel.

test/mv_web/components/member_filter_component_test.exs

@@ -8,7 +8,10 @@ defmodule MvWeb.Components.MemberFilterComponentTest do
   - Button label and badge logic
   - Filtering to show only boolean custom fields
   """
-  # async: false to prevent PostgreSQL deadlocks when running LiveView tests against DB
+  # Kept async: false. The deferrable-FK migration removed the concurrent
+  # create_member deadlock, but this file additionally showed an async-isolation
+  # failure under load (filtered members from a parallel test leaking in), so it
+  # is not trivially async-safe; resolving that is a separate follow-up.
   use MvWeb.ConnCase, async: false
 
   import Phoenix.LiveViewTest

test/mv_web/member_live/index_custom_fields_display_test.exs

@@ -9,7 +9,10 @@ defmodule MvWeb.MemberLive.IndexCustomFieldsDisplayTest do
   - Custom field values are correctly formatted for different types
   - Members without custom field values show empty cell or "-"
   """
-  # async: false to prevent PostgreSQL deadlocks when creating members and custom fields
+  # Kept async: false as a deferred scope decision. The deferrable-FK migration
+  # removed the concurrent-create_member deadlock that previously forced this, so
+  # re-flipping this members/custom-fields suite to async is a possible follow-up
+  # rather than part of the original change.
   use MvWeb.ConnCase, async: false
   import Phoenix.LiveViewTest
   require Ash.Query

test/mv_web/member_live/index_field_visibility_test.exs

@@ -10,7 +10,10 @@ defmodule MvWeb.MemberLive.IndexFieldVisibilityTest do
   - Integration with member list display
   - Custom fields visibility
   """
-  # async: false to prevent PostgreSQL deadlocks when creating members and custom fields
+  # Kept async: false as a deferred scope decision. The deferrable-FK migration
+  # removed the concurrent-create_member deadlock that previously forced this, so
+  # re-flipping this members/custom-fields suite to async is a possible follow-up
+  # rather than part of the original change.
   use MvWeb.ConnCase, async: false
 
   import Phoenix.LiveViewTest

test/mv_web/member_live/index_groups_accessibility_test.exs

@@ -8,7 +8,10 @@ defmodule MvWeb.MemberLive.IndexGroupsAccessibilityTest do
   - Sort header has aria-label for screen reader
   - Keyboard navigation works (Tab through filter, sort header)
   """
-  # async: false to prevent PostgreSQL deadlocks when creating members and groups
+  # Kept async: false as a deferred scope decision. The deferrable-FK migration
+  # removed the concurrent-create_member deadlock that previously forced this, so
+  # re-flipping this members/groups suite to async is a possible follow-up rather
+  # than part of the original change.
   use MvWeb.ConnCase, async: false
   import Phoenix.LiveViewTest
   require Ash.Query

test/mv_web/member_live/index_groups_display_test.exs

@@ -8,7 +8,10 @@ defmodule MvWeb.MemberLive.IndexGroupsDisplayTest do
   - No badge for members without groups
   - Badge shows group name correctly
   """
-  # async: false to prevent PostgreSQL deadlocks when creating members and groups
+  # Kept async: false as a deferred scope decision. The deferrable-FK migration
+  # removed the concurrent-create_member deadlock that previously forced this, so
+  # re-flipping this members/groups suite to async is a possible follow-up rather
+  # than part of the original change.
   use MvWeb.ConnCase, async: false
   import Phoenix.LiveViewTest
   require Ash.Query

test/mv_web/member_live/index_groups_filter_test.exs

@@ -6,7 +6,10 @@ defmodule MvWeb.MemberLive.IndexGroupsFilterTest do
   All / Yes / No (per group). Multiple active group filters combine with AND
   (member must match all selected group conditions).
   """
-  # async: false to prevent PostgreSQL deadlocks when creating members and groups
+  # Kept async: false as a deferred scope decision. The deferrable-FK migration
+  # removed the concurrent-create_member deadlock that previously forced this, so
+  # re-flipping this members/groups suite to async is a possible follow-up rather
+  # than part of the original change.
   use MvWeb.ConnCase, async: false
   import Phoenix.LiveViewTest
   require Ash.Query

test/mv_web/member_live/index_groups_integration_test.exs

@@ -10,7 +10,10 @@ defmodule MvWeb.MemberLive.IndexGroupsIntegrationTest do
   - Groups work with existing search (but not testing search integration itself)
   - Member index search by group name returns members in that group (Issue #375)
   """
-  # async: false to prevent PostgreSQL deadlocks when creating members and groups
+  # Kept async: false as a deferred scope decision. The deferrable-FK migration
+  # removed the concurrent-create_member deadlock that previously forced this, so
+  # re-flipping this members/groups suite to async is a possible follow-up rather
+  # than part of the original change.
   use MvWeb.ConnCase, async: false
   import Phoenix.LiveViewTest
   require Ash.Query

test/mv_web/member_live/index_groups_performance_test.exs

@@ -8,7 +8,10 @@ defmodule MvWeb.MemberLive.IndexGroupsPerformanceTest do
   - Filter works at database level (not in-memory)
   - Sort runs in-memory but uses preloaded group data (no extra DB queries)
   """
-  # async: false to prevent PostgreSQL deadlocks when creating members and groups
+  # Kept async: false as a deferred scope decision. The deferrable-FK migration
+  # removed the concurrent-create_member deadlock that previously forced this, so
+  # re-flipping this members/groups suite to async is a possible follow-up rather
+  # than part of the original change.
   use MvWeb.ConnCase, async: false
   import Phoenix.LiveViewTest
   require Ash.Query

test/mv_web/member_live/index_groups_sorting_test.exs

@@ -2,7 +2,10 @@ defmodule MvWeb.MemberLive.IndexGroupsSortingTest do
   @moduledoc """
   Tests for sorting by groups in the member overview.
   """
-  # async: false to prevent PostgreSQL deadlocks when creating members and groups
+  # Kept async: false as a deferred scope decision. The deferrable-FK migration
+  # removed the concurrent-create_member deadlock that previously forced this, so
+  # re-flipping this members/groups suite to async is a possible follow-up rather
+  # than part of the original change.
   use MvWeb.ConnCase, async: false
   import Phoenix.LiveViewTest
   require Ash.Query

test/mv_web/member_live/index_groups_url_params_test.exs

@@ -9,7 +9,10 @@ defmodule MvWeb.MemberLive.IndexGroupsUrlParamsTest do
   - URL parameters work with other parameters (query, sort_field, etc.)
   - URL is bookmarkable (filter/sorting persist)
   """
-  # async: false to prevent PostgreSQL deadlocks when creating members and groups
+  # Kept async: false. The deferrable-FK migration removed the concurrent
+  # create_member deadlock, but this file additionally showed an async-isolation
+  # failure under load (filtered members from a parallel test leaking in), so it
+  # is not trivially async-safe; resolving that is a separate follow-up.
   use MvWeb.ConnCase, async: false
   import Phoenix.LiveViewTest
   require Ash.Query

test/mv_web/member_live/show_groups_display_test.exs

@@ -10,8 +10,10 @@ defmodule MvWeb.MemberLive.ShowGroupsDisplayTest do
   - Accessibility: group links have aria-label for screen readers
 
   ## Note on async
-  async: false to avoid PostgreSQL deadlocks when creating members and groups
-  in the same test run (same as IndexGroupsDisplayTest).
+  Kept async: false as a deferred scope decision. The deferrable-FK migration
+  removed the concurrent-create_member deadlock that previously forced this, so
+  re-flipping this members/groups suite to async is a possible follow-up rather
+  than part of the original change.
   """
   use MvWeb.ConnCase, async: false
   import Phoenix.LiveViewTest

test/mv_web/user_live/form_test.exs

@@ -1,5 +1,8 @@
 defmodule MvWeb.UserLive.FormTest do
-  # async: false to prevent PostgreSQL deadlocks when creating members and users
+  # Kept async: false as a deferred scope decision. The deferrable-FK migration
+  # removed the concurrent-create_member deadlock that previously forced this, so
+  # re-flipping this members/users suite to async is a possible follow-up rather
+  # than part of the original change.
   use MvWeb.ConnCase, async: false
   import Phoenix.LiveViewTest