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)

mac/locator.h

@@ -32,6 +32,13 @@ public:
     // errors (found by the error gallery, 2026-08-22).  Locator() is for
     // logging; errors either carry a real document location or this.
     static Locator none() { return Locator(fs::path{}, -1, -1); }
+    // The inverse of str(): "[<file>:<line>.<column>]" back to a Locator.
+    // A klammer implementation receives its position as the STATE value
+    // K_loc, which is that string; without this it can only pass a
+    // default-constructed Locator, which captures the C++ source location
+    // and prints a file no user can act on.  Anything unparseable gives
+    // none() -- a missing location beats a wrong one.
+    static Locator from_string(const std::string& s);
     std::string str(bool relative = false) const;
     std::string desc(bool relative = false) const;
     std::string abbrev(bool include_chr=true) const;