fix(jobs): enqueue jobs after transaction commit to fix SyncJob deserialization race (#2354)

* fix(jobs): enqueue jobs after transaction commit to fix SyncJob deserialization race

Syncable#sync_later creates a Sync row and enqueues SyncJob inside the
same transaction. Rails 7.2 deferred such enqueues until commit by
default; Rails 8.0 changed the default to enqueue immediately and 8.1
left the global config toggle non-functional, so a worker could dequeue
the job before COMMIT, fail to resolve the Sync GlobalID
(ActiveJob::DeserializationError), and have it silently dropped by
discard_on -- surfacing as stuck syncs after the Rails 8.1 upgrade.

Set enqueue_after_transaction_commit = true on ApplicationJob (the
Rails 8.2 default, inherited by every job) and drop the dead :never
symbol override on DestroyJob. Add regression and invariant tests.

* test(jobs): use OpenStruct for DestroyJob failure case

Replace the bare mock and the respond_to? expectation (an implementation
detail of how DestroyJob probes the model) with an OpenStruct that genuinely
responds to scheduled_for_deletion. Keeps only the command-facing assertions:
destroy raises and update! is called with scheduled_for_deletion: false.
Matches the repo convention of preferring OpenStruct for mock instances.

* test(snaptrade): assert connection-cleanup enqueue defers until commit

SnaptradeAccount#after_destroy enqueues SnaptradeConnectionCleanupJob, which
references the item/account by id. Before the ApplicationJob fix, Rails 8.1
enqueued it immediately inside the destroy transaction, so a worker could run
before COMMIT, see the not-yet-deleted row in its shared-authorization guard,
skip the provider call, and leak the SnapTrade connection. This regression
test destroys an account inside a transaction and asserts the job is not
enqueued until the transaction commits.

test/models/snaptrade_account_test.rb

@@ -1,6 +1,8 @@
 require "test_helper"
 
 class SnaptradeAccountTest < ActiveSupport::TestCase
+  include ActiveJob::TestHelper
+
   setup do
     @family_a = families(:dylan_family)
     @family_b = families(:empty)
@@ -71,4 +73,32 @@ class SnaptradeAccountTest < ActiveSupport::TestCase
       )
     end
   end
+
+  # Regression: the after_destroy callback enqueues SnaptradeConnectionCleanupJob,
+  # which references the account/item by id. If it is enqueued before the destroy
+  # transaction commits (Rails 8.1's immediate-enqueue default), a worker can run
+  # before COMMIT: its "do other accounts still share this authorization?" guard
+  # then sees the not-yet-deleted row, skips the provider call, and leaks the
+  # SnapTrade connection. Enqueuing must be deferred until commit.
+  test "connection cleanup job is deferred until the destroy transaction commits" do
+    account = SnaptradeAccount.create!(
+      snaptrade_item: @item_a,
+      snaptrade_account_id: "cleanup_uuid",
+      snaptrade_authorization_id: "auth_cleanup",
+      name: "Brokerage",
+      currency: "USD",
+      current_balance: 1000
+    )
+
+    enqueued_mid_transaction = nil
+
+    ActiveRecord::Base.transaction do
+      account.destroy!
+      enqueued_mid_transaction = enqueued_jobs.any? { |job| job[:job] == SnaptradeConnectionCleanupJob }
+    end
+
+    assert_not enqueued_mid_transaction,
+      "SnaptradeConnectionCleanupJob was enqueued before the destroy committed (would race COMMIT and leak the provider connection)"
+    assert_enqueued_with job: SnaptradeConnectionCleanupJob
+  end
 end