Add all IntelliJ settings to gitignore #206
Description
While upgrading to Gradle 9, I noticed a few things that changed locally in my .idea/ directory, which has happened before, and mostly related to local setup (some related to which JDK I'm using, for example) or settings that IntelliJ will auto-generate (some change may be related to upgrading to IntelliJ 2025.2 today). I propose adding the .idea directory in its entirety to the .gitignore.