Windows: product names, the editors, WSL; the Linux page's image step

Assembled from development commit c3c40f6c8fca. Since 830b193: on Windows the
products carry Windows names (ktext.exe, klammertext.dll, document.dll,
reflect.dll) and the console's output code page is UTF-8 for a run; the
editor tooling works on Windows (VS Code, Sublime Text, Vim, with the
interpreter's name chosen by platform) and Notepad++ joins it
(doc/edit/notepadpp: a User Defined Language and two Run-menu commands);
a sixth install page, doc/install/windows_wsl_install.md, for Linux
inside WSL; the Windows page opens with the three routes and gains its
editor section, the PowerShell quoting and Path notes; the Linux page
installs OpenImageIO from the python3-openimageio package and verifies
with kdiag --machine; the README lists all six install pages. Linux and
macOS behaviour is unchanged.

doc/edit/README.md

@@ -1,7 +1,7 @@
 # Klammertext editor support
 
 Editing support for Klammertext files (`.kt` documents and `.k` klammer
-definitions) in four editors, built around one shared implementation.
+definitions) in five editors, built around one shared implementation.
 
 | Directory | Contents |
 |---|---|
@@ -10,6 +10,7 @@ definitions) in four editors, built around one shared implementation.
 | `sublime/` | Sublime Text package.  Syntax file plus thin plugin wrappers that import the shared core directly (Sublime's plugin host is Python). |
 | `vim/` | Vim plugin.  Syntax/ftplugin files plus commands that run the shared core's CLI; with `+python3`, the core also runs in-process (`=` operator, live match highlighting). |
 | `vscode/` | Visual Studio Code extension.  TextMate grammar plus a dependency-free extension that spawns the language server and speaks LSP to it. |
+| `notepadpp/` | Notepad++ (Windows).  A User Defined Language for the highlighting, and two Run-menu commands that pass the current file through the shared core's CLI (delimiter check, reindent).  No plugin host, so nothing structural runs in-process. |
 
 ## The architecture
 
@@ -41,7 +42,8 @@ document/range formatting (reindentation), documentHighlight and
 definition (the matcher), and a `klammertext.alignTable` command.  The
 VS Code extension is its first client; any LSP client works — Neovim's
 built-in LSP, Emacs eglot, Sublime's LSP package — with a one-line
-configuration pointing at `python3 klammertext_ls.py`.
+configuration pointing at `python3 klammertext_ls.py` (on Windows
+`python klammertext_ls.py`).
 
 Syntax highlighting and cursor-latency features stay native in each editor
 (a tokenizer or a per-keystroke matcher cannot round-trip to Python), so
@@ -68,10 +70,12 @@ Two kinds of artifact cannot read it and restate parts of it by hand:
    defcustoms, checked byte-for-byte against the shared core by
    `tst/editor_test.sh`.
 2. **The static syntax files** — the literal-klammer set (`@code`) appears
-   in the Sublime `.sublime-syntax`, the Vim `syntax/klammertext.vim`, and
-   the VS Code `tmLanguage.json` grammar (and the Emacs defcustom).  When
-   you add a literal klammer, change them together; each file's header
-   carries the same SYNC note.
+   in the Sublime `.sublime-syntax`, the Vim `syntax/klammertext.vim`, the
+   VS Code `tmLanguage.json` grammar, and the Notepad++ `Klammertext.udl.xml`
+   (and the Emacs defcustom).  When you add a literal klammer, change them
+   together; each file's header carries the same SYNC note.  The UDL can
+   hold only names that are not prefixes of other klammer names (it has
+   no word boundary), so it carries `code` and not `c`.
 
 ## Testing