test(config): verify Vim/Neovim config payload parity

Expose the init_options payload builders publicly in both clients
(M.init_options/M.server_settings in Lua, nuwiki#lsp#settings() in Vim) so
they can be inspected. Add editor harnesses that dump each client's
server-bound config as deterministic key=value lines and diff against a
shared golden file: nvim == golden and vim == golden together prove the two
clients send identical config. Add a server-side test asserting the Vim flat
shape and the Neovim {nuwiki:{...}} wrapper desugar to the same WikiConfig.
Wire both harnesses into CI.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

development/tests/config-expected.txt

@@ -0,0 +1,17 @@
+[default]
+wiki_root=~/vimwiki
+file_extension=.wiki
+syntax=vimwiki
+log_level=warn
+[sample]
+wiki_root=/tmp/base
+file_extension=.md
+syntax=vimwiki
+log_level=debug
+wikis[0].diary_rel_path=journal
+wikis[0].file_extension=.wiki
+wikis[0].index=home
+wikis[0].name=personal
+wikis[0].root=/tmp/personal
+wikis[1].name=work
+wikis[1].root=/tmp/work