Kernova tooling 0.1.6-beta

Kernova tooling 0.1.6-beta

Tooling changes:

• Added changelog generation that compares rebuilds with the previous matching manifest and avoids duplicating generated sections from manual notes.
• Hardened CurseForge upload metadata by rejecting invalid environment IDs.
• Made Modrinth uploads idempotent when the target version already exists.
• Improved VartaPack Doctor launching with Java override support, runtime diagnostics, and a vendored Gson dependency.

Validation:

• updater/.venv/bin/python -m unittest discover -s updater/tests
• updater/.venv/bin/kernova-update validate --artifacts
• Publish upload dry-run skipped because no Modrinth .mrpack or CurseForge .zip artifacts are present under publish/.

Modpack publishing was intentionally not performed, and the PackPing public feed was not pushed.

Remaining manual work:

• None for the tooling release.