Windows is installed through WSL; the native Windows build is withdrawn (from dev a9756dac74c6)

Klammertext on Windows is the Linux build inside WSL 2, or the prebuilt
containers through Docker Desktop. The native build from source (MSYS2) is
no longer offered:

- doc/install/windows_source_install.md and the bundled shell under win/
  are removed.
- doc/install/windows_wsl_install.md is the Windows page. It says there is
  no native build, and its editor section says what holds for each editor:
  Emacs, Vim and Visual Studio Code (through its WSL extension) as on
  Linux; Sublime Text and Notepad++ on the Windows side, with their
  self-contained packages, on files opened through \\wsl.localhost.
- The README lists six install guides; the Notepad++ and VS Code READMEs
  no longer refer to the MSYS2 shell.

No change to the language, the Standard Klammer Set or the commands.

doc/install/windows_wsl_install.md

@@ -1,9 +1,8 @@
 # Klammertext on Windows through the Windows Subsystem for Linux
 
-This page is for someone who works in Linux by habit and has a Windows
-machine to work on. The Windows Subsystem for Linux (WSL 2) runs a real
-Linux kernel and an ordinary Ubuntu inside Windows, and Klammertext's
-Linux installation applies there unchanged: the same compiler, the same
+This is how Klammertext is installed on Windows. The Windows Subsystem
+for Linux (WSL 2) runs a real Linux kernel and an ordinary Ubuntu inside
+Windows, and Klammertext's Linux installation applies there unchanged: the same compiler, the same
 Python, the same TeX Live, the same `runtime.env`. So this page is short.
 It gets you to an Ubuntu prompt, sends you to the Linux page, and then
 says what is specific to living in WSL: where files belong, how to look
@@ -11,10 +10,10 @@ at the output from Windows, and how the Windows editors reach the Linux
 side. The steps were followed on a Windows 11 machine with WSL 2.7 and
 the Ubuntu it installs today, 26.04.
 
-There are two other ways to have Klammertext on Windows: as native
-Windows programs built from source (`windows_source_install.md`), and
-from the prebuilt container images, which this page covers at the end,
-since Docker runs inside WSL as it runs on Linux.
+The commands are Linux programs, run from the Ubuntu prompt; there is no
+native Windows build. The other way to have Klammertext on Windows is the
+prebuilt container images, which this page covers at the end, since
+Docker runs inside WSL as it runs on Linux.
 
 
 ## Getting Linux
@@ -114,11 +113,16 @@ are a separate list and do not run in WSL windows.)
 **Emacs and Vim** are Linux programs: `sudo apt-get install emacs` or
 `vim`, then the Emacs and Vim packages under `doc/edit/` as on Linux.
 
-**Sublime Text and Notepad++** on Windows can open the Linux files
-through `\\wsl.localhost\Ubuntu\...` and highlight them with their
-Klammertext packages (`doc/edit/sublime/`, `doc/edit/notepadpp/`); their
-commands that run the shared core would run the Windows `python`, so for
-those two editors the native Windows installation is the better fit.
+**Sublime Text and Notepad++** on Windows open the Linux files through
+`\\wsl.localhost\Ubuntu\...`, with their Klammertext packages
+(`doc/edit/sublime/`, `doc/edit/notepadpp/`) installed on the Windows
+side. The packages are self-contained: they highlight, and their commands
+-- matching delimiters, reindentation, table alignment, the delimiter
+check -- are Python programs that never run Klammertext itself, so the
+Linux side is not involved. Sublime Text runs them in its own
+interpreter. Notepad++'s Run commands, and the optional language server
+for Sublime Text, start `python`, which means a Python for Windows from
+python.org on the `Path`.
 
 
 ## The container route