fix(tables): don't skip escaped \| in cell scan — match the server

The server lexer (nuwiki-rs) splits table cells on a backslash-escaped `\|`
(it can't skip it yet without leaving a stray backslash in the output), but
the client's cell_bar_positions was skipping `\|`. That made the editor
auto-align keep `a\|b` as one cell while HTML export split it into two.

Drop the `\|` case from both clients so buffer alignment and export agree.
`[[…]]` / `{{…}}` / `` `code` `` pipes are still treated as literal. A
coordinated `\|` follow-up (server unescaping + client re-adding the skip)
is tracked in nuwiki-rs.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

lua/nuwiki/commands.lua

@@ -823,18 +823,19 @@ local is_table_row = require('nuwiki.util').is_table_row
 
 -- 1-based byte positions of the cell-separator `|` characters in `s`. Pipes
 -- that are literal cell content are skipped: those inside `[[…]]` wikilinks,
--- `{{…}}` transclusions, `` `…` `` inline code, and backslash-escaped `\|`.
--- This keeps a `[[url|title]]` link in one cell instead of splitting on its
--- internal pipe.
+-- `{{…}}` transclusions, and `` `…` `` inline code. This keeps a
+-- `[[url|title]]` link in one cell instead of splitting on its internal pipe.
+--
+-- Backslash-escaped `\|` is intentionally NOT skipped, to match the server
+-- lexer (nuwiki-rs), which can't skip it yet without leaving a stray backslash
+-- in the output. See nuwiki-rs issue for the coordinated `\|` follow-up.
 local function cell_bar_positions(s)
   local out = {}
   local i = 1
   local n = #s
   while i <= n do
     local c = s:sub(i, i)
-    if c == '\\' then
-      i = i + 2 -- skip the escaped char (e.g. `\|`)
-    elseif c == '`' then
+    if c == '`' then
       local close = s:find('`', i + 1, true)
       i = (close or n) + 1
     elseif s:sub(i, i + 1) == '[[' then