value keyword for Value Classes

### Description

Introduce recognition of the value keyword in Java source files to support[ Valhalla Early Access builds](https://jdk.java.net/valhalla/) (OpenJDK 26 and beyond). This enhancement would ensure correct syntax highlighting, parsing, and code completion for the new Value Objects feature introduced under Project Valhalla.

### Use case/motivation

The OpenJDK team is standardizing Value Objects as part of Project Valhalla. With the introduction of the value keyword in early-access builds of OpenJDK 26, IDE support is essential for developers testing and adopting this feature. NetBeans should recognize the value keyword similarly to existing Java keywords (e.g., record, sealed, permits) to maintain feature parity and developer experience with other IDEs.

### Related issues

_No response_

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

No

No files or tests are named. Start by locating how NetBeans handles existing Java keywords such as record, sealed, and permits, then trace the syntax highlighting, parsing, and code-completion entry points. Done means Java sources using value receive equivalent IDE support for the Valhalla Early Access syntax.

Written by the indexing model from the issue text.