Remove Rust code, delegate server to nuwiki-rs repo

Delete all Rust crates (crates/) and Cargo files. The nuwiki-ls binary
is now built in the separate nuwiki-rs repository and downloaded at
install time from the Gitea release assets, with a cargo build fallback
that clones nuwiki-rs.

Update all documentation to reflect the split repo layout.

lua/nuwiki/commands.lua

@@ -816,8 +816,7 @@ end
 -- the cursor visually mid-cell after columns expand. For insert-mode
 -- editing we replicate the alignment logic locally so we can realign
 -- *before* placing the cursor, all in a single `vim.schedule` tick.
--- The algorithm matches `crates/nuwiki-lsp/src/commands.rs::ops::
--- render_aligned_table`.
+-- The algorithm matches the LSP server's implementation in nuwiki-rs.
 
 local function is_table_row(line)
   return line ~= nil and line:match('^%s*|.*|%s*$') ~= nil

lua/nuwiki/folding.lua

@@ -1,6 +1,6 @@
 -- lua/nuwiki/folding.lua — `foldexpr` fallback when the LSP isn't
 -- attached. Same heading-block model as the server-side `foldingRange`
--- provider in `crates/nuwiki-lsp/src/folding.rs`, but driven from a
+-- provider in the nuwiki-rs LSP server, but driven from a
 -- pure regex over `getline()` so it works without a running server.
 --
 -- Activated by `setlocal foldmethod=expr foldexpr=v:lua.require'nuwiki.folding'.expr()`

lua/nuwiki/install.lua

@@ -2,9 +2,9 @@
 --
 -- Strategy:
 --   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.
+--   2. If missing, download a release asset for the current target from
+--      nuwiki-rs.
+--   3. On failure, fall back to cloning nuwiki-rs and building with cargo.
 
 local M = {}
 
@@ -51,16 +51,30 @@ local function build_from_source(dest)
     return false
   end
   local root = plugin_root()
-  vim.notify('nuwiki: building from source (cargo build --release) …', vim.log.levels.INFO)
+  vim.notify('nuwiki: building nuwiki-ls from source (cargo build --release) …', vim.log.levels.INFO)
+  local rs_repo = vim.fn.fnamemodify(root, ':h:h') .. '/nuwiki-rs'
+  if not vim.uv then vim.uv = vim.loop end
+  local rs_exists = vim.uv.fs_stat(rs_repo)
+  if not rs_exists then
+    vim.notify('nuwiki: cloning nuwiki-rs …', vim.log.levels.INFO)
+    local _ = vim.fn.system({
+      'git', 'clone', '--depth', '1',
+      'https://code.gfran.co/gffranco/nuwiki-rs.git', rs_repo,
+    })
+    if vim.v.shell_error ~= 0 then
+      vim.notify('nuwiki: failed to clone nuwiki-rs', vim.log.levels.ERROR)
+      return false
+    end
+  end
   local _ = vim.fn.system({
     'cargo', 'build', '--release', '-p', 'nuwiki-ls',
-    '--manifest-path', root .. '/Cargo.toml',
+    '--manifest-path', rs_repo .. '/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()
+  local built = rs_repo .. '/target/release/nuwiki-ls' .. exe_suffix()
   vim.fn.system({ 'cp', built, dest })
   vim.fn.system({ 'chmod', '+x', dest })
   return vim.fn.executable(dest) == 1
@@ -74,11 +88,8 @@ local function download_release(dest)
   if vim.fn.executable('curl') ~= 1 or vim.fn.executable('tar') ~= 1 then
     return false
   end
-  -- Gitea serves the most recent release under the `latest` tag segment
-  -- (`/releases/download/latest/<asset>`). Note this is NOT GitHub's
-  -- `/releases/latest/download/<asset>` shape, which Gitea 404s.
   local url = string.format(
-    'https://code.gfran.co/gffranco/nuwiki/releases/download/latest/nuwiki-ls-%s.tar.gz',
+    'https://code.gfran.co/gffranco/nuwiki-rs/releases/download/latest/nuwiki-ls-%s.tar.gz',
     target
   )
   local archive = vim.fn.tempname() .. '.tar.gz'
@@ -101,9 +112,6 @@ 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