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/notepadpp/README.md

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+# Klammertext support for Notepad++
+
+Notepad++ support for editing Klammertext files (`.kt` documents and `.k`
+klammer definitions): syntax highlighting through a **User Defined
+Language**, and the shared editor core's delimiter check and
+reindentation through two **Run-menu commands**. Notepad++ is Windows
+only, and so is this package.
+
+Notepad++ has no Python plugin host and no built-in language-server
+client, so it cannot import the shared core the way Sublime Text does or
+talk to the language server the way VS Code does. What it has is a
+declarative highlighter and a Run menu that can invoke any program on the
+current file, and this package uses exactly those two things.
+
+## Files
+
+| File | Purpose |
+|---|---|
+| `Klammertext.udl.xml` | The User Defined Language: highlighting for the three `@`-tiers, escapes, text removal, and the `@code` verbatim interior. Its header lists what it colours and the limits of a UDL. |
+| `klammertext_edit.py` | The shared editor core (in the editing zip it sits here; in the Klammertext repository it is `doc\edit\shared\klammertext_edit.py`). The Run commands call it. |
+| `README.md` | This file. |
+
+## Requirements
+
+- Notepad++ 7.9 or later (the `userDefineLangs` folder; any recent
+  version qualifies).
+- For the Run commands: `python` on the `Path`, which the Klammertext
+  installation already needs.
+
+## Install the highlighting
+
+Copy `Klammertext.udl.xml` into Notepad++'s user-defined-language folder
+and restart Notepad++:
+
+```powershell
+$d = "$env:AppData\Notepad++\userDefineLangs"
+New-Item -ItemType Directory -Force $d | Out-Null
+Copy-Item Klammertext.udl.xml $d
+```
+
+Notepad++ loads every file in that folder at start. `.kt` and `.k` files
+then open as "Klammertext" (the language shows in the status bar and at
+the bottom of the **Language** menu). The alternative is the dialog:
+**Language ￫ User Defined Language ￫ Define your language… ￫ Import…**,
+which copies the file to the same place.
+
+What you see: klammer applications (`@name … @`) in blue, definitions
+(`@@name … @@`) in green, system commands (`@@@name … @@@`) in orange;
+a `#` at the start of a line greys the rest of the line, `#[ … ]#` greys
+and folds a region; `##`, `#-`, `#+`, `#/`, `|` and `:` in the marker
+red; the interior of `@code … code@` muted and uninterpreted. The
+colours are the palette's light-ground values with transparent
+backgrounds, so a dark theme keeps its own ground.
+
+Two limits, both properties of a UDL rather than of Klammertext, are
+documented in the file's header: a `#` that is not the first thing on
+its line is not treated as a comment (so that the whitespace operators
+`#-`, `#+`, `#/` never grey the rest of their line), and `@c … c@` is not
+made verbatim (a UDL delimiter has no word boundary, so `@c` would also
+open at `@caption` and `@cond`).
+
+## The Run commands
+
+The shared core's command-line interface reads a file on standard input
+and writes the result on standard output; Notepad++'s **Run ￫ Run…**
+dialog (`F5`) runs a command line with the current file's path filled in
+as `$(FULL_CURRENT_PATH)`. Two commands cover the structural tools.
+Replace `C:\Users\<you>\klammertext\doc\edit\shared` with the folder that
+holds `klammertext_edit.py` (with the editing zip, the folder this
+README is in).
+
+**Check the delimiters** — lists every unclosed opening, extra close,
+name or tier mismatch, and unclosed literal span or `#[` block, as
+`line:column: message`; an empty window means the file is balanced.
+The `/k` keeps the window open to read:
+
+```
+cmd /k python "C:\Users\<you>\klammertext\doc\edit\shared\klammertext_edit.py" check < "$(FULL_CURRENT_PATH)"
+```
+
+**Reindent the file** — rewrites the file with the canonical
+indentation (2 spaces per nesting level, bars and closes at their
+opener's column, `@document` transparent, verbatim and removed text
+untouched):
+
+```
+cmd /c python "C:\Users\<you>\klammertext\doc\edit\shared\klammertext_edit.py" indent < "$(FULL_CURRENT_PATH)" > "$(FULL_CURRENT_PATH).tmp" && move /y "$(FULL_CURRENT_PATH).tmp" "$(FULL_CURRENT_PATH)"
+```
+
+Paste each line into the Run dialog once, press **Save…**, give it a
+name ("Klammertext check", "Klammertext reindent") and a shortcut
+(`Ctrl+Alt+K`, `Ctrl+Alt+I` are free); they then appear at the bottom of
+the **Run** menu with those keys.
+
+Two things to know about the reindent command. It works on the file
+**on disk**, so save first (`Ctrl+S`); Notepad++ does not save before
+running. And after it runs, Notepad++ notices the changed file: with the
+default setting it asks whether to reload, which you answer Yes; under
+**Settings ￫ Preferences ￫ MISC. ￫ File Status Auto-Detection** the
+choice "Update silently" makes the reload automatic. Undo history is
+lost on a reload, as for any external edit.
+
+Table alignment and jump-to-match need a caret position the Run dialog
+cannot pass, so they are not offered here. They are available in every
+other supported editor, and for Notepad++ through the PythonScript
+plugin, which embeds a Python that can import the shared core and reach
+the caret; a script for it is a possible addition, not part of this
+package.
+
+## Keeping things in sync
+
+The UDL restates the literal-klammer set (`@code`) that the shared core
+owns in `LITERAL_KLAMMERS`; its header says how to add one. The editor
+support's overview is `doc/edit/README.md` in the Klammertext repository.