refactor(custom-comments): collapse the divider and box generator duplication

Three near-identical skeletons folded together: the simple divider becomes the
padded divider with zero text padding; the plain box and the heavy box share one
border/text/border emitter (cj/--comment-box-emit) with a HEAVY flag adding the
interior blank lines; and the repeated cmt-start/doubled-semicolon/space line
prologue becomes cj/--comment-emit-prefix. Output is byte-identical -- the
per-generator characterization suites stay green -- and the file drops ~65 lines.

0 files changed, 0 insertions, 0 deletions