* New SQL wrapper function `fetchInt()`
* Favour use of `fetchAssoc()`, `fetchInt()`, `fetchColumn()`
* Favour Nowdoc / Heredoc syntax for SQL
* Update indenting to PHP 8.1+ convention
* Favour `bindValue()` instead of position `?` when possible
* Favour `bindValue()` over `bindParam()`
* More uniform and robust syntax when using `bindValue()`, checking return code
* Stable IDs during SQL import
Follow-up of https://github.com/FreshRSS/FreshRSS/pull/7949
Make sure that the original category IDs, feed IDs, and label IDs are kept identical during an SQL import.
Avoid breaking everything referring to categories, feeds, labels by their IDs such as searches and third-party extensions.
* Fix export of default category
