Fix and cleanup

Problem/Motivation

`paste()` fires inverted event constants
Fixed in `src/Controller/ApiController.php`: captured return values of `attachToRoot()`/
`attachToSlot()` as `$new_node_id`, corrected dispatch to
`$is_paste_root ? ON_ATTACH_TO_ROOT : ON_ATTACH_TO_SLOT`, and pass `$new_node_id`
(not `$parent_id`) as the node_id argument.

`HistoryInterface::setNewPresent()` — interface does not match implementation
Fixed in `src/HistoryInterface.php`: added `bool $index = TRUE` as 4th parameter to
align the interface contract with the `Instance` implementation.

`Profile::debug` is not exported to config
Removed `$debug` property, `isDebugModeActivated()` from `Profile` and `ProfileInterface`,
`debug` entry from config schema, and `dbDebug` from `ProfileViewBuilder`. The property
was unused in JS/templates so removal was safe.

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes