Start and end balance anchors for historical account balances (#2455)

* Add kind field to valuation

* Fix schema conflict

* Add kind to valuation

* Scaffold opening balance manager

* Opening balance manager implementation

* Update account import to use opening balance manager + tests

* Update account to use opening balance manager

* Fix test assertions, usage of current balance manager

* Lint fixes

* Add Opening Balance manager, add tests to forward calculator

* Add credit card to "all cash" designation

* Simplify valuation model

* Add current balance manager with tests

* Add current balance logic to reverse calculator and plaid sync

* Tweaks to initial calc logic

* Ledger testing helper, tweak assertions for reverse calculator

* Update test assertions

* Extract balance transformer, simplify calculators

* Algo simplifications

* Final tweaks to calculators

* Cleanup

* Fix error, propagate sync errors up to parent

* Update migration script, valuation naming

test/models/account_import_test.rb

@@ -0,0 +1,92 @@
+require "test_helper"
+
+class AccountImportTest < ActiveSupport::TestCase
+  include ActiveJob::TestHelper, ImportInterfaceTest
+
+  setup do
+    @subject = @import = imports(:account)
+  end
+
+  test "import creates accounts with valuations" do
+    import_csv = <<~CSV
+      type,name,amount,currency
+      depository,Main Checking,1000.00,USD
+      depository,Savings Account,5000.00,USD
+    CSV
+
+    @import.update!(
+      raw_file_str: import_csv,
+      entity_type_col_label: "type",
+      name_col_label: "name",
+      amount_col_label: "amount",
+      currency_col_label: "currency"
+    )
+
+    @import.generate_rows_from_csv
+
+    # Create mappings for account types
+    @import.mappings.create! key: "depository", value: "Depository", type: "Import::AccountTypeMapping"
+
+    @import.reload
+
+    # Store initial counts
+    initial_account_count = Account.count
+    initial_entry_count = Entry.count
+    initial_valuation_count = Valuation.count
+
+    # Perform the import
+    @import.publish
+
+    # Check if import succeeded
+    if @import.failed?
+      fail "Import failed with error: #{@import.error}"
+    end
+
+    assert_equal "complete", @import.status
+
+    # Check the differences
+    assert_equal initial_account_count + 2, Account.count, "Expected 2 new accounts"
+    assert_equal initial_entry_count + 2, Entry.count, "Expected 2 new entries"
+    assert_equal initial_valuation_count + 2, Valuation.count, "Expected 2 new valuations"
+
+    # Verify accounts were created correctly
+    accounts = @import.accounts.order(:name)
+    assert_equal [ "Main Checking", "Savings Account" ], accounts.pluck(:name)
+    assert_equal [ 1000.00, 5000.00 ], accounts.map { |a| a.balance.to_f }
+
+    # Verify valuations were created with correct fields
+    accounts.each do |account|
+      valuation = account.valuations.last
+      assert_not_nil valuation
+      assert_equal "opening_anchor", valuation.kind
+      assert_equal account.balance, valuation.entry.amount
+    end
+  end
+
+  test "column_keys returns expected keys" do
+    assert_equal %i[entity_type name amount currency], @import.column_keys
+  end
+
+  test "required_column_keys returns expected keys" do
+    assert_equal %i[name amount], @import.required_column_keys
+  end
+
+  test "mapping_steps returns account type mapping" do
+    assert_equal [ Import::AccountTypeMapping ], @import.mapping_steps
+  end
+
+  test "dry_run returns expected counts" do
+    @import.rows.create!(
+      entity_type: "depository",
+      name: "Test Account",
+      amount: "1000.00",
+      currency: "USD"
+    )
+
+    assert_equal({ accounts: 1 }, @import.dry_run)
+  end
+
+  test "max_row_count is limited to 50" do
+    assert_equal 50, @import.max_row_count
+  end
+end