phase 9: editor glue — plugin, LSP wiring, install, health, docs

P5 + P6 resolved (SPEC §11): Neovim 0.11+ and Vim 9.1+.

Universal Vim entry:
- plugin/nuwiki.vim dispatches Vim vs Neovim. Neovim path waits for
  the user's `require('nuwiki').setup()` call; Vim path starts the
  LSP client on `FileType vimwiki` and exposes `:NuwikiInstall`.
- ftdetect/nuwiki.vim associates `*.wiki` with the `vimwiki` filetype.
- ftplugin/nuwiki.vim sets commentstring + comments + formatoptions +
  suffixesadd + iskeyword, with a clean `b:undo_ftplugin`.
- syntax/nuwiki.vim ships default `@vimwiki*` highlight links for the
  semantic-token legend (with `level1..6` + `centered` modifiers),
  plus a minimal regex fallback so static highlighting works before
  the LSP attaches.

Lua glue (Neovim 0.11+):
- init.lua exposes setup() / install() / health() — wiring only per
  SPEC §6.2.
- config.lua holds the §7.5 schema (wiki_root / file_extension /
  syntax / log_level) and a tbl_deep_extend apply().
- lsp.lua registers via `vim.lsp.config{} + vim.lsp.enable` on 0.11+;
  falls back to a FileType autocmd calling `vim.lsp.start` on older
  builds. Root dir walks up for `.git` / `.nuwiki`, then uses
  wiki_root.
- install.lua does target-triple detection (Linux gnu/musl x x86_64/
  aarch64, macOS arm/x86, Windows), curl+tar download from the
  release URL, cp/chmod into bin/, with a cargo fallback. Honours
  `g:nuwiki_build_from_source`.
- health.lua implements `:checkhealth nuwiki` per §7.6.

VimL glue (Vim 9.1+):
- autoload/nuwiki/lsp.vim follows §7.4 preference order:
  vim-lsp (calls `lsp#register_server`) → coc.nvim (prints the
  coc-settings.json snippet) → error.
- scripts/download_bin.vim mirrors the Lua installer for Dein /
  vim-plug build hooks — same target triples, same download →
  fallback → cargo build chain.

Help: doc/nuwiki.txt with tags for install (lazy.nvim / vim-plug /
Dein), config options, health, LSP feature list, `:NuwikiInstall`.

Rust workspace unchanged this phase; 172 tests still green locally.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

lua/nuwiki/install.lua

@@ -1,6 +1,113 @@
--- lua/nuwiki/install.lua — binary download / build-from-source.
--- Implementation deferred to Phase 9 (Editor Glue).
+-- lua/nuwiki/install.lua — install / build the `nuwiki-ls` binary.
+--
+-- Strategy (matches SPEC §7.2):
+--   1. Look for `bin/nuwiki-ls[.exe]` next to the plugin.
+--   2. If missing or `g:nuwiki_build_from_source` is set, build with cargo.
+--   3. Otherwise try to download a release asset for the current target.
+--      On failure, fall back to cargo.
 
 local M = {}
 
+local function plugin_root()
+  local source = debug.getinfo(1, 'S').source:sub(2)
+  return vim.fn.fnamemodify(source, ':h:h:h')
+end
+
+local function exe_suffix()
+  return vim.fn.has('win32') == 1 and '.exe' or ''
+end
+
+function M.expected_path()
+  return plugin_root() .. '/bin/nuwiki-ls' .. exe_suffix()
+end
+
+function M.is_installed()
+  return vim.fn.executable(M.expected_path()) == 1
+end
+
+local function target_triple()
+  if vim.fn.has('win32') == 1 then
+    return 'x86_64-pc-windows-msvc'
+  elseif vim.fn.has('mac') == 1 then
+    if vim.fn.has('arm64') == 1 or jit and jit.arch == 'arm64' then
+      return 'aarch64-apple-darwin'
+    end
+    return 'x86_64-apple-darwin'
+  elseif vim.fn.has('linux') == 1 then
+    local uname = vim.uv and vim.uv.os_uname() or vim.loop.os_uname()
+    local musl = (vim.fn.system('ldd --version 2>&1'):find('musl') ~= nil)
+    if uname.machine == 'aarch64' or uname.machine == 'arm64' then
+      return musl and 'aarch64-unknown-linux-musl' or 'aarch64-unknown-linux-gnu'
+    end
+    return musl and 'x86_64-unknown-linux-musl' or 'x86_64-unknown-linux-gnu'
+  end
+  return nil
+end
+
+local function build_from_source(dest)
+  if vim.fn.executable('cargo') ~= 1 then
+    vim.notify('nuwiki: cargo not found, cannot build from source',
+               vim.log.levels.ERROR)
+    return false
+  end
+  local root = plugin_root()
+  vim.notify('nuwiki: building from source (cargo build --release) …', vim.log.levels.INFO)
+  local _ = vim.fn.system({
+    'cargo', 'build', '--release', '-p', 'nuwiki-ls',
+    '--manifest-path', root .. '/Cargo.toml',
+  })
+  if vim.v.shell_error ~= 0 then
+    vim.notify('nuwiki: cargo build failed', vim.log.levels.ERROR)
+    return false
+  end
+  local built = root .. '/target/release/nuwiki-ls' .. exe_suffix()
+  vim.fn.system({ 'cp', built, dest })
+  vim.fn.system({ 'chmod', '+x', dest })
+  return vim.fn.executable(dest) == 1
+end
+
+local function download_release(dest)
+  local target = target_triple()
+  if not target then
+    return false
+  end
+  if vim.fn.executable('curl') ~= 1 or vim.fn.executable('tar') ~= 1 then
+    return false
+  end
+  local url = string.format(
+    'https://code.gfran.co/gffranco/nuwiki/releases/latest/download/nuwiki-ls-%s.tar.gz',
+    target
+  )
+  local archive = vim.fn.tempname() .. '.tar.gz'
+  vim.fn.system({ 'curl', '-fsSL', '-o', archive, url })
+  if vim.v.shell_error ~= 0 then
+    return false
+  end
+  local extract = vim.fn.tempname()
+  vim.fn.mkdir(extract, 'p')
+  vim.fn.system({ 'tar', '-xzf', archive, '-C', extract })
+  if vim.v.shell_error ~= 0 then
+    return false
+  end
+  vim.fn.system({ 'cp', extract .. '/nuwiki-ls' .. exe_suffix(), dest })
+  vim.fn.system({ 'chmod', '+x', dest })
+  return vim.fn.executable(dest) == 1
+end
+
+function M.install()
+  local dest = M.expected_path()
+  vim.fn.mkdir(vim.fn.fnamemodify(dest, ':h'), 'p')
+
+  if vim.g.nuwiki_build_from_source == 1 then
+    return build_from_source(dest)
+  end
+  if download_release(dest) then
+    vim.notify('nuwiki: installed ' .. dest, vim.log.levels.INFO)
+    return true
+  end
+  vim.notify('nuwiki: download failed, falling back to source build',
+             vim.log.levels.WARN)
+  return build_from_source(dest)
+end
+
 return M