Unicode sequences, @typeface, and the font/typeface distinction

A run of Unicode code points now needs one pair of carets, not one pair
each: ^9053 53EF 9053^ renders the characters adjacently, and a single
character inside such a run stands for itself.  An invalid code point is
an error naming the position that wrote it, rather than an apology
rendered into the finished document; noncharacters are refused alongside
surrogates; and a code point that lands on a Klammertext special is safe
through the re-reads that assemble a document.  The character tables now
produce the precomposed form, so a diacritic written as ^a" and one typed
directly are the same text to a search or a copy-paste.

"kdesc -u" describes how to write a Unicode character, with tables of
glyphs beside the codes that produce them.  It is new and not yet
complete: it predates the sequence form and the typeface klammer below.

A typeface and a style are no longer both called "font".  A typeface is a
family resolved by name; a style code is the one letter naming a type
style.  So @document takes :serif_typeface and its siblings, a table takes
:style, captions take :caption_style and :caption_size, the uniform scale
is :text_scale, and the command is "kdesc --typeface".  This renames
arguments a document may already use; an old name is a located error
rather than a silent omission.

@typeface sets a passage in another typeface for the length of that
passage:

    @typeface Noto Sans Egyptian Hieroglyphs | ^132AA 133CF^ :scale 1.5 @

Writing the klammer is the whole declaration -- the document resolves the
typeface, embeds it in what it produces, and carries its license along.
Two typefaces for scripts no text font covers now ship with Klammertext:
Noto Sans Egyptian Hieroglyphs and Noto Sans Cuneiform.  Every typeface in
the distribution now carries its license file.

(from dev 61e598698891)

tst/kdesc_test.sh

@@ -83,6 +83,18 @@ shows " 1. -k lists klammers"              '@table'            "$KDESC" -k
 shows " 2. -t lists targets"               'html'              "$KDESC" -t
 shows " 3. -c lists character codes"       '.'                 "$KDESC" -c
 shows " 4. -i reads the named input"       '@x'                "$KDESC" -i "$DIR/split.k" -k
+# -u describes how to write a Unicode character.  Asserted by OUTCOME, on
+# the two things the section must carry however its prose is rewritten:
+# the ^...^ notation it teaches, and a rendered character beside its code
+# point -- the whole point of the section is that a reader sees the glyph
+# they are about to write.  It does NOT pin the prose, which is meant to
+# grow (as of 2026-08-25 the section predates the sequence form and the
+# typeface klammer, and does not yet mention either).
+shows " 4a. -u describes the Unicode syntax" '\^0418\^'        "$KDESC" -u
+# The rendered glyph, as UTF-8 BYTE escapes: macOS ships bash 3.2, which
+# expands $'\xHH' but not $'\U...' (that difference failed this suite's
+# sibling on Olion, 2026-08-23).
+shows " 4b. ... and shows the characters"    $'\xf0\x93\x8a\xaa' "$KDESC" -u
 
 echo
 echo "-- the multi-letter topics --"