fix: collapse quicktype column alignment for gofmt compatibility

quicktype emits wide-spaced struct fields for column alignment, but
gofmt doesn't column-align when fields have interleaved comments.
Added post-processing to collapse excessive spacing in quicktype
struct field lines and remove trailing blank lines from quicktype
output.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: stephentoub