Add support for Node.js v26 #1017

Description

NAN currently supports Node.js up to v25, but fails to compile with Node.js v26.

Environment

• NAN Version: 2.26.2
• Node.js Version: 26.0.0
• Platform: Linux (cross-platform issue)

Reproduction

Building native addon with NAN and Node.js v26 fails during compilation.

Expected Behavior

NAN should compile successfully with Node.js v26.

Actual Behavior

Compilation fails with multiple V8 API compatibility errors.