Code quality: Loose equality (==) used instead of strict equality (===) throughout codebase

[Eistee82]

Description

The codebase uses loose equality `==` and `!=` instead of strict equality `===` and `!==` in hundreds of places across `main.js`, `lib/database.js`, `lib/vis.js`, `lib/actor_ext.js`, `lib/cronjobs.js`, and other files.

Impact: Loose equality can lead to unexpected type coercion bugs. While most current usages work correctly, this is a maintenance risk.

Note: This is a large-scale change that should be done in a separate dedicated PR with thorough testing, as each comparison needs to be verified individually.

[github-actions]

Dieses Ticket wurde seit 5 Monaten nicht aktualisiert. Es wird in 7 Tagen automatisch geschlossen.
This ticket has not been updated for 5 months. It will be closed automatically in 7 days.

[github-actions]

Ticket wegen Inaktivität automatisch geschlossen.
This ticket has been closed due to inactivity.