can't see old local history after NB upgrade

### Apache NetBeans version

Apache NetBeans 29

### What happened

I have attempted an upgrade from v25 to 28 and v29 and both times I can't see my "Local history" for source code
I have verified the \var\filehistory folders are identical from v25 to v29.
Local history does work after the upgrade but I can't any of my change history prior to the upgrade

### Language / Project Type / NetBeans Component

PHP

### How to reproduce

1. install v25 and make source code changes
2. verify history data is viewable
3. upgrade v29 and open source code and verify "history" tab doesn't show any changes/diff

### Did this work correctly in an earlier version?

No / Don't know

### Operating System

Windows 11

### JDK

Oracle JDK "26"

### Apache NetBeans packaging

Apache NetBeans platform

### Anything else

Has the file format of the "filehistory" changes from v25 or v26?

### Are you willing to submit a pull request?

No

Reproduce the upgrade from NetBeans 25 to 29 on Windows 11 using the PHP project steps, then inspect how the \var\filehistory data is read when the History tab opens. Compare the behavior before and after the upgrade, including the reported file-format concern. Done means pre-upgrade history is visible after upgrading while new local history still works.

Written by the indexing model from the issue text.