Family sharing (#1272)

* Initial account sharing changes

* Update schema.rb

* Update schema.rb

* Change sharing UI to modal

* UX fixes and sharing controls

* Scope include in finances better

* Update totals.rb

* Update totals.rb

* Scope reports to finance account scope

* Update impersonation_sessions_controller_test.rb

* Review fixes

* Update schema.rb

* Update show.html.erb

* FIX db validation

* Refine edit permissions

* Review items

* Review

* Review

* Add application level helper

* Critical review

* Address remaining review items

* Fix modals

* more scoping

* linter

* small UI fix

* Fix: Sync broadcasts push unscoped balance sheet to all users

* Update sync_complete_event.rb

 The fix removes the sidebar broadcasts (which rendered unscoped account groups using family.balance_sheet without user context)
  along with the now-unused sidebar_targets, account_group, and family_balance_sheet private methods.

  The sidebar will still update correctly — when the sync completes, Family::SyncCompleteEvent#broadcast fires family.broadcast_refresh, which triggers a
  morph-based page refresh for each user with their own authenticated session, rendering properly scoped sidebar content.

db/migrate/20260324100000_add_account_sharing_support.rb

@@ -0,0 +1,21 @@
+class AddAccountSharingSupport < ActiveRecord::Migration[7.2]
+  def change
+    # Family-level default: whether new accounts are shared with all members by default
+    add_column :families, :default_account_sharing, :string, default: "shared", null: false
+
+    # Account ownership: who created/owns the account
+    add_reference :accounts, :owner, type: :uuid, foreign_key: { to_table: :users }, null: true, index: true
+
+    # Sharing join table: per-user access to accounts they don't own
+    create_table :account_shares, id: :uuid, default: -> { "gen_random_uuid()" } do |t|
+      t.references :account, type: :uuid, null: false, foreign_key: true
+      t.references :user, type: :uuid, null: false, foreign_key: true
+      t.string :permission, null: false, default: "read_only"
+      t.boolean :include_in_finances, null: false, default: true
+      t.timestamps
+    end
+
+    add_index :account_shares, [ :account_id, :user_id ], unique: true
+    add_index :account_shares, [ :user_id, :include_in_finances ]
+  end
+end

db/migrate/20260324100001_backfill_account_owners_and_shares.rb

@@ -0,0 +1,34 @@
+class BackfillAccountOwnersAndShares < ActiveRecord::Migration[7.2]
+  def up
+    # Existing families keep current behavior: all accounts shared
+    Family.update_all(default_account_sharing: "shared")
+
+    # For each family, assign all accounts to the admin (or first user)
+    Family.find_each do |family|
+      admin = family.users.find_by(role: %w[admin super_admin]) || family.users.order(:created_at).first
+      next unless admin
+
+      family.accounts.where(owner_id: nil).update_all(owner_id: admin.id)
+
+      # Create shares for non-owner members (preserves current full-access behavior)
+      member_ids = family.users.where.not(id: admin.id).pluck(:id)
+      account_ids = family.accounts.pluck(:id)
+
+      if member_ids.any? && account_ids.any?
+        records = member_ids.product(account_ids).map do |user_id, account_id|
+          { user_id: user_id, account_id: account_id, permission: "full_control",
+            include_in_finances: true, created_at: Time.current, updated_at: Time.current }
+        end
+
+        AccountShare.upsert_all(records, unique_by: %i[account_id user_id])
+      end
+    end
+
+    # Owner is enforced at the model level via before_validation callback
+    # Keeping nullable at DB level for backward compatibility with tests/seeds
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end

db/migrate/20260324100002_add_check_constraints_to_sharing_columns.rb

@@ -0,0 +1,6 @@
+class AddCheckConstraintsToSharingColumns < ActiveRecord::Migration[7.2]
+  def change
+    add_check_constraint :families, "default_account_sharing IN ('shared', 'private')", name: "chk_families_default_account_sharing"
+    add_check_constraint :account_shares, "permission IN ('full_control', 'read_write', 'read_only')", name: "chk_account_shares_permission"
+  end
+end

db/migrate/20260324100003_change_accounts_owner_fk_to_nullify.rb

@@ -0,0 +1,11 @@
+class ChangeAccountsOwnerFkToNullify < ActiveRecord::Migration[7.2]
+  def up
+    remove_foreign_key :accounts, :users, column: :owner_id
+    add_foreign_key :accounts, :users, column: :owner_id, on_delete: :nullify
+  end
+
+  def down
+    remove_foreign_key :accounts, :users, column: :owner_id
+    add_foreign_key :accounts, :users, column: :owner_id
+  end
+end