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/target/latex_util.py

@@ -81,9 +81,9 @@ def minipage(content, width="\\textwidth", vertical="c", center=True, vmargin=""
 
 def offset_length(offset):
     r"""An :offset as a LaTeX length, or "0pt" when there is none."""
-    if not offset or offset in ("0", "0pt"):
+    if not offset or offset in ("0", "0pt", "0.0"):
         return "0pt"
-    return kutil.parse_length("tex", offset, 1)[0]
+    return kutil.parse_width("tex", offset)[0]
 
 def offset_space(offset):
     r"""An :offset as an \hspace*, or "" when there is none."""
@@ -111,7 +111,7 @@ def caption_wrapper(element, hpos, bottom_margin=0, offset=None):
         return minipage("\\hfill" + element + inset, vmargin=vmargin, center=False)
     if hpos == "none":
         return element
-    length, _, _ = kutil.parse_length("tex", hpos, 1)
+    length, _, _ = kutil.parse_width("tex", hpos)
     return minipage(f"\\hspace*{{{length}}}" + element + "\\hfill",
                     vmargin=vmargin, center=False)