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/argtype_registry.cpp

@@ -13,7 +13,10 @@
 
 Parameter_set& Argtype_registry::parameters()
 {
-    static Parameter_set instance("name | desc :pattern .* :python_cast str :default :alone");
+    // desc.klammertext: the description is Klammertext, kept exactly as
+    // written (Argtype::m_desc) for a Machine to render -- kdesc's listing,
+    // the Handbook.  Plain-text displays (an argument error) unquote it.
+    static Parameter_set instance("name | desc.klammertext :pattern .* :python_cast str :default :alone");
     return instance;
 }
 
@@ -205,6 +208,8 @@ std::string Argtype_registry::describe(bool long_form, int indent_width) const
         int pat_width = name_width + 2 + indent_width + label.size();
         result << indent << std::setw(name_width) << name << sp_arrow;
         if (long_form) {
+            // The stored text, as written: this is the programmer's dump
+            // (kdiag --machine), and a quoted "^@" in it is the fact.
             result << m_types.at(name).m_desc << "\n";
             result << std::setw(pat_width) << "regex: " << m_types.at(name).m_symbolic_pattern;
             if (m_types.at(name).m_symbolic_pattern != m_types.at(name).m_pattern)