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/test-config.lua

@@ -0,0 +1,74 @@
+-- development/tests/test-config.lua — dump the Neovim client's
+-- `initialization_options` payload for two scenarios (default config and a
+-- representative multi-wiki sample) as deterministic `key=value` lines.
+--
+-- The runner (test-config.sh) diffs the output against
+-- development/tests/config-expected.txt. The Vim harness
+-- (test-config-vim.vim) emits byte-identical lines against the SAME golden,
+-- so "nvim == golden" and "vim == golden" together prove the two clients
+-- send the same server-bound config — i.e. Vim/Neovim config parity.
+--
+-- Only the server-relevant keys are emitted (wiki_root, file_extension,
+-- syntax, log_level, wikis[*]). `mappings`/`folding` are client-side
+-- concerns the server ignores, so they're intentionally excluded.
+
+local out = assert(os.getenv('NUWIKI_CONFIG_OUT'), 'NUWIKI_CONFIG_OUT unset')
+
+local config = require('nuwiki.config')
+local lsp = require('nuwiki.lsp')
+
+local lines = {}
+local function emit(s)
+  lines[#lines + 1] = s
+end
+
+local function dump(payload)
+  emit('wiki_root=' .. tostring(payload.wiki_root))
+  emit('file_extension=' .. tostring(payload.file_extension))
+  emit('syntax=' .. tostring(payload.syntax))
+  emit('log_level=' .. tostring(payload.log_level))
+  if payload.wikis then
+    for i, w in ipairs(payload.wikis) do
+      local keys = {}
+      for k in pairs(w) do
+        keys[#keys + 1] = k
+      end
+      table.sort(keys)
+      for _, k in ipairs(keys) do
+        emit(string.format('wikis[%d].%s=%s', i - 1, k, tostring(w[k])))
+      end
+    end
+  end
+end
+
+-- Scenario 1: defaults (no user config, no VimL globals).
+vim.g.nuwiki_wikis = nil
+config.apply({})
+emit('[default]')
+dump(lsp.init_options())
+
+-- Scenario 2: representative config exercising scalar keys + a wikis list.
+config.apply({
+  wiki_root = '/tmp/base',
+  file_extension = '.md',
+  syntax = 'vimwiki',
+  log_level = 'debug',
+  wikis = {
+    {
+      name = 'personal',
+      root = '/tmp/personal',
+      file_extension = '.wiki',
+      index = 'home',
+      diary_rel_path = 'journal',
+    },
+    { name = 'work', root = '/tmp/work' },
+  },
+})
+emit('[sample]')
+dump(lsp.init_options())
+
+local f = assert(io.open(out, 'w'))
+f:write(table.concat(lines, '\n') .. '\n')
+f:close()
+
+vim.cmd('qa!')