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>

com/ktext.cpp

@@ -70,7 +70,12 @@ int main(int argc, char* argv[])
             M.read(fs::path(p));
         }
 
-        std::string result = trim(M.apply(target));
+        // Trim NEWLINES only, as Machine::apply itself does: a leading space
+        // is content under txt -- the indent of a block that opens the
+        // document (a table, a definition list) -- and trim() took it off
+        // the first line alone, every other line keeping its indent
+        // (TODO #60, 2026-09-13).
+        std::string result = trim_char(M.apply(target), '\n');
         if (display_only && !result.empty()) {
             std::cout << result << "\n";
         } else if (!result.empty()) {