chore(repo): drop redundant package.json ignore/override pair

[ottobolyos]

Summary

Drops a redundant ignore/override pair from `.gitignore`: the broad `package.json` + `package-lock.json` ignore plus the `!docs/package.json` + `!docs/package-lock.json` overrides that re-allow the docs site's manifest.

• The repo is C#/.NET; the only npm-using surface is `docs/` (VitePress).
• No other `package.json` files exist in the tree that need to be ignored.
• Removing the broad ignore + the override pair leaves `docs/package.json` and `docs/package-lock.json` tracked naturally, with simpler `.gitignore` semantics.

[ottobolyos]

Closing -- the gitignore cleanup belongs inside #157 (the VitePress docs PR) as an atomic commit there, not as a separate PR. Folded back into #157 at its tip.