Editor support generalized: shared core, language server, Vim and VS Code (from dev eb5baf9cbe59)

doc/edit/ now holds a shared Python implementation of the language's
structural layer (klammertext_edit.py) and a dependency-free language
server (klammertext_ls.py), with integrations for Emacs, Sublime Text,
Vim, and Visual Studio Code.  The editor test suite in tst/ covers the
core's API and CLI, the language server protocol, the VS Code
extension, headless Vim, and Emacs byte-equality.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

doc/edit/vim/ftplugin/klammertext.vim

@@ -0,0 +1,63 @@
+" Klammertext filetype plugin: comment format, the structural commands, and
+" (when Vim has +python3) fast in-process indentation and live delimiter
+" match highlighting.  The implementations are in autoload/klammertext.vim;
+" the algorithms themselves are the shared Python core
+" (klammertext_edit.py — see doc/edit/README.md for how it is located).
+"
+" Commands (buffer-local):
+"   :[range]KlammertextReindent   reindent the range (default: whole buffer)
+"   :KlammertextAlign             align the @table enclosing the cursor
+"   :KlammertextJumpToMatch       jump between a klammer application's
+"                                 opening and closing delimiter
+"   :KlammertextCheck             unbalanced/mismatched delimiters -> the
+"                                 location list
+"
+" Default mappings (set g:klammertext_no_mappings to define none):
+"   <LocalLeader>i   reindent the current line (visual: the selection)
+"   <LocalLeader>a   align the enclosing table
+"   <LocalLeader>j   jump to the matching delimiter
+"
+" Reindentation is EXPLICIT-ONLY: whitespace is content in Klammertext, so
+" indentkeys is emptied and nothing reformats as a side effect of typing.
+" With +python3 the ftplugin also sets 'indentexpr', so the = operator
+" (e.g. ==, gg=G) reindents through the same shared implementation.
+
+if exists("b:did_ftplugin")
+  finish
+endif
+let b:did_ftplugin = 1
+
+setlocal commentstring=#\ %s
+setlocal comments=b:#
+setlocal indentkeys=
+
+command! -buffer -range=% KlammertextReindent
+      \ call klammertext#Reindent(<line1>, <line2>)
+command! -buffer KlammertextAlign call klammertext#AlignTable()
+command! -buffer KlammertextJumpToMatch call klammertext#JumpToMatch()
+command! -buffer KlammertextCheck call klammertext#Check()
+
+if !exists("g:klammertext_no_mappings")
+  nnoremap <buffer> <silent> <LocalLeader>i :.KlammertextReindent<CR>
+  xnoremap <buffer> <silent> <LocalLeader>i :KlammertextReindent<CR>
+  nnoremap <buffer> <silent> <LocalLeader>a :KlammertextAlign<CR>
+  nnoremap <buffer> <silent> <LocalLeader>j :KlammertextJumpToMatch<CR>
+endif
+
+let b:undo_ftplugin = "setlocal commentstring< comments< indentkeys<"
+      \ . " | delcommand KlammertextReindent"
+      \ . " | delcommand KlammertextAlign"
+      \ . " | delcommand KlammertextJumpToMatch"
+      \ . " | delcommand KlammertextCheck"
+
+" With +python3 the shared core runs in-process: 'indentexpr' makes the =
+" operator work, and the matching delimiter is highlighted live as the
+" cursor sits on one (the show-paren equivalent; a mismatch shows in red
+" with a message).  Without +python3 the commands above still work — they
+" shell out to python3 — and Neovim users can get live matching from the
+" language server instead (see doc/edit/README.md).
+if has('python3')
+  setlocal indentexpr=klammertext#IndentExpr()
+  let b:undo_ftplugin .= " | setlocal indentexpr<"
+  call klammertext#SetupMatchHighlight()
+endif