Width and height argtypes, kdesc --argtypes from ref/, txt @define/@left_right/@columns, kdiag --check value validation (from dev d6993110e9b3)

Also: the klammertext argtype (descriptions kept as source), txt table
wrapping and :hpos/:offset, @c between ‹ ›, txt section headings, the
ktext newline-only trim, capitalize(), and the argtype test suite.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

sks/image/image.k

@@ -34,7 +34,7 @@
 @@image.k
   basename
   :id
-  :width.length .5w
+  :width.width .5w
   @caption_args@
   :vmargin.bool true
   @hpos_args@