Validate and normalize auto-postpone period to days (#2672)

* Validate and normalize auto-postpone period to days

- Add Entropy::AUTO_POSTPONE_PERIODS and validate auto_postpone_period against the allowed set
- Introduce auto_postpone_period_in_days for forms and entropy update endpoints
- Fall back to index 0 in knob partial when current value isn't in options
- Remove entropy_auto_close_options helper in favor of model constant
- Update tests to use allowed period values

* Use auto_postpone_period_in_days for JSON entropy updates

The JSON API was accepting auto_postpone_period (seconds) which
bypassed the days normalization and validation. Switch to
auto_postpone_period_in_days consistently and add explicit
wrap_parameters so flat JSON params are wrapped correctly for
the virtual attribute.

* Default to account or 30-day fallback when knob value is invalid

* Address PR review feedback for entropy validation

- Fall back to first knob option (index 0) when persisted value isn't in
  the allowed set, preventing nil index errors for legacy values
- Use integer division (1.day.to_i) for consistent day calculations

* Default to account entropy period instead of first option for knob fallback

* Test that default auto-postpone period is in the allowed periods

* Return 422 instead of 500 for invalid entropy auto-postpone values

Rescue ActiveRecord::RecordInvalid in entropy controllers so invalid
auto_postpone_period_in_days values return 422 Unprocessable Entity
instead of raising a 500.

* Fix NoMethodError when board entropy falls back to account default

Use container.account.entropy.auto_postpone_period_in_days instead of
container.account.auto_postpone_period_in_days since Account doesn't
delegate that method.

* Test board entropy fallback to account default for invalid periods

test/controllers/boards_controller_test.rb

@@ -41,12 +41,22 @@ class BoardsControllerTest < ActionDispatch::IntegrationTest
     assert_response :success
   end
 
+  test "edit renders 11-day auto-close option last on the knob" do
+    get edit_board_path(boards(:writebook))
+    assert_response :success
+
+    assert_select "input[type=radio][name='board[auto_postpone_period_in_days]']" do |options|
+      assert_equal Entropy::AUTO_POSTPONE_PERIODS_IN_DAYS.map(&:to_s), options.map { |option| option["value"] }
+      assert_equal "11", options.last["value"]
+    end
+  end
+
   test "update" do
     patch board_path(boards(:writebook)), params: {
       board: {
         name: "Writebook bugs",
         all_access: false,
-        auto_postpone_period: 1.day
+        auto_postpone_period_in_days: 7
       },
       user_ids: users(:kevin, :jz).pluck(:id)
     }
@@ -54,7 +64,7 @@ class BoardsControllerTest < ActionDispatch::IntegrationTest
     assert_redirected_to edit_board_path(boards(:writebook))
     assert_equal "Writebook bugs", boards(:writebook).reload.name
     assert_equal users(:kevin, :jz).sort, boards(:writebook).users.sort
-    assert_equal 1.day, entropies(:writebook_board).auto_postpone_period
+    assert_equal 7.days, entropies(:writebook_board).auto_postpone_period
     assert_not boards(:writebook).all_access?
   end