Clean up packages in JabKit

[koppor]

Follow-up to #14271

I see that we need a @Command for jabkit, but also a "wrapper" around to initialiize. Currently, the class name is not consistent to the command - this fixes it.

• entry point: JabKitLauncher
• command "jabkit": JabKit

Also cleans up packages - removes cli; our toolkit is already the CLI.

Steps to test

• Run JabKit Launcher
• jbang .jbang/JabKitLauncher

Mandatory checks

• I own the copyright of the code submitted and I license it under the MIT license
• I manually tested my changes in running JabRef (always required)
• [/] I added JUnit tests for changes (if applicable)
• [/] I added screenshots in the PR description (if change is visible to the user)
• [/] I described the change in CHANGELOG.md in a way that is understandable for the average user (if change is visible to the user)
• [/] I checked the user documentation: Is the information available and up to date? If not, I created an issue at https://github.com/JabRef/user-documentation/issues or, even better, I submitted a pull request updating file(s) in https://github.com/JabRef/user-documentation/tree/main/en.

[koppor]

Locally, JBang runs

$ jbang .jbang/JabKitLauncher.java
2025-11-17 10:41:31 [main] org.jabref.logic.preferences.JabRefCliPreferences.getFetcherKeysFromKeyring()
WARN: JabRef could not open the key store