fix(keymaps): correct Neovim global diary tab/tomorrow maps (map_prefix audit)

A map_prefix parity audit against upstream vimwiki found the Neovim global
entry-point block in lua/nuwiki/init.lua carried the same collision the Vim
global + buffer-local maps were already fixed for: <prefix><Leader>t was
bound to tomorrow and <prefix><Leader>m (tomorrow) was missing entirely.

Now <prefix><Leader>t opens today in a new tab and <prefix><Leader>m is
tomorrow — consistent with plugin/nuwiki.vim, the buffer-local maps, and
upstream (VimwikiTabMakeDiaryNote / VimwikiMakeTomorrowDiaryNote).

Adds global_maps.diary_tab_and_tomorrow_targets to test-keymaps.lua (queries
in a scratch buffer so buffer-local maps don't shadow the globals). Logs the
fix plus a new "RSS feed structure fidelity" gap (the audit confirmed the
custom_wiki2html arg contract and base_url scope are faithful; only the RSS
document shape diverges) in development/vimwiki-gap.md.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

development/tests/test-keymaps.lua

@@ -850,6 +850,33 @@ vim.defer_fn(function()
     if not ok then error(err) end
   end)
 
+  -- ===== Global (non-buffer) entry-point diary maps =====
+  -- init.lua _setup_global_mappings ran during setup(). Regression guard for
+  -- the audit-found bug: <prefix><Leader>t must be today-in-a-tab and
+  -- <prefix><Leader>m must be tomorrow (matching the Vim global side +
+  -- upstream), not the old wiring that dropped `m` and bound `t` to tomorrow.
+  -- Query in a scratch (non-vimwiki) buffer so the buffer-local maps don't
+  -- shadow the globals.
+  tobj_case('global_maps.diary_tab_and_tomorrow_targets', function()
+    local buf = vim.api.nvim_create_buf(false, true)
+    vim.api.nvim_set_current_buf(buf)
+    local function gdesc(lhs)
+      local d = vim.fn.maparg(lhs, 'n', false, true)
+      if vim.tbl_isempty(d) then return nil end
+      return d.desc or ''
+    end
+    local ok, err = pcall(function()
+      local t = gdesc('<Leader>w<Leader>t')
+      local m = gdesc('<Leader>w<Leader>m')
+      if not t then error('<Leader>w<Leader>t global map missing') end
+      if not m then error('<Leader>w<Leader>m global map missing (tomorrow)') end
+      if not t:find('tab') then error('<Leader>w<Leader>t should be today-in-tab, desc=' .. t) end
+      if not m:find('tomorrow') then error('<Leader>w<Leader>m should be tomorrow, desc=' .. m) end
+    end)
+    vim.api.nvim_buf_delete(buf, { force = true })
+    if not ok then error(err) end
+  end)
+
   -- ===== Wiki picker (config-driven, no LSP) =====
   -- The picker must build its list from config so it works from any buffer
   -- before the server attaches.