vajson Library: Initial contribution & integration into S‑CORE

[4og]

This increment focuses on the initial onboarding of the vajson library into the S‑CORE. The goal is to publish the vajson code in an incubation repository and enable it to build using the S‑CORE toolchain. This establishes the technical foundation for subsequent product increments, where vajson will be migrated into the Baselibs repository and its safety artifacts aligned with the S‑CORE Process.

Acceptance criteria

• The vajson component request is reviewed, approved, and merged.
• The vajson library source code is published and accessible in the GitHub repository: https://github.com/eclipse-score/inc_json
• The vajson library builds successfully using the S‑CORE build ecosystem (C++ toolchain, tooling, GitHub workflows)