[Bug]: Hop Web Explorer refresh can trigger Invalid thread access in GitCommitPerspective

### Apache Hop version?

2.20.0-SNAPSHOT-20260903

### Java version?

21

### Operating system

Docker

### What happened?

This error was encountered during normal Hop Web use. The code analysis below was assisted by Codex and the suspected cause still needs confirmation.

In a multi-session environment I encountered:

SWTException: Invalid thread access
at Text.setText
at GitCommitPerspective.retrieveState
at GitGuiPlugin.rootChanged
at ExplorerPerspective.refresh

No Git operation was performed.

"GitGuiPlugin.rootChanged()" calls "GitCommitPerspective.getInstance()". If the current session cannot find its own perspective, "getInstance()" falls back to the JVM-wide static "instance".

This may allow a session-bound Explorer callback to obtain a Git perspective belonging to another session, which is consistent with the observed stack trace.

I have not been able to reproduce this reliably.

Observed on "apache/hop-web:2.20.0-SNAPSHOT-20260903", Java 21, Docker/Linux ARM64.

Related: #8047, #8108

### Issue Priority

Priority: 3

### Issue Component

Component: Hop Web