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>

mac/util.h

@@ -46,6 +46,17 @@ std::vector<std::string> word_split(const std::string& s);
 // whose description happens to fit one line and miss the identically worded
 // one that does not.
 std::string collapse_whitespace(const std::string& s);
+// Klammertext source shown as PLAIN text: "^" before an ASCII punctuation
+// character is removed ("^@date" -> "@date"), nothing else changes.  For an
+// error message or a log line that quotes a literal description; a display
+// that can render should hand the source to a Machine instead.
+std::string unquote_punctuation(const std::string& s);
+
+// The string with its first character in upper case ("table" -> "Table").
+// ASCII only: a non-ASCII first byte is left as it is, since a std::string
+// is bytes and the standard library has no Unicode case mapping.  Unlike
+// Python's str.capitalize(), the rest of the string is untouched.
+std::string capitalize(std::string s);
 
 // Case-insensitive substring test, ASCII folding only.  The project takes no
 // ICU or locale dependency (the same rule as the language tables and