fix(security): improve atomic file write and handle encryption key placement

- Throw `RandomException` for better error reporting in `atomicWriteFile`.
- Simplify Windows-specific `rename()` fallback logic.
- Fix `encryption.key` assignment order to ensure consistency in `.env` updates.

Signed-off-by: objecttothis <17935339+objecttothis@users.noreply.github.com>
This commit is contained in:
Internal Server Error - Gitea: Git with a cup of tea
500 Internal Server Error

Gitea Version: 1.28.0+dev-477-g8b6ad49a5f