chore: bump version to 0.15.0

[striderZA]

Summary

Bump the project version from 0.14.1 to 0.15.0 so the tag-based release workflow accepts v0.15.0.

Related issue

N/A

Type of change

• Bug fix
• New feature
• Refactor
• Documentation
• Build / CI

Test plan

• cmake --build build
• ctest --test-dir build --output-on-failure -E "Benchmark|test_ui|ADC DDC output grid spans"
• Manual verification steps (if applicable):
  • Verified CMakeLists.txt now contains project (RfSimulator VERSION 0.15.0)
  • Verified the release workflow checks the tag against CMakeLists.txt, so v0.15.0 will match

Checklist

• My code follows the existing code style (see .clang-format)
• I ran clang-format -i on changed files (N/A: no C++ file changes)
• I added or updated tests where appropriate (N/A: version-only change)
• Existing tests still pass