test(keymaps): Vim path harness + fix 25 broken one-liner functions

User asked about the Vim path of the keymap suite. Building it
surfaced a real bug: 25 of our autoload functions were written as
`function! foo() abort | call bar() | endfunction` one-liners, which
isn't valid Vim syntax — `function!` requires a multi-line body, and
Vim parses the `|` after `abort` as an unexpected trailing character
(E488). Most invocations of the buggy autoload functions errored
out the moment Vim tried to parse them, which is why the user saw
broken keymaps and confusing diagnostics.

Rewrote all 25 one-liners (`autoload/nuwiki/commands.vim`) into the
standard three-line form. Affected groups: `diary_*`, `toggle_list_item`,
`cycle_list_item`, `reject_list_item`, `heading_add`, `heading_remove`,
`toc_generate`, `links_generate`, `export_current` / `_all` /
`_all_force` / `_rss`, and the §13.1 deferred stubs (`list_change_lvl`,
`list_remove_done`, `table_*`, `colorize`, `paste_link`, `paste_url`).

Added `scripts/test-keymaps-vim.{sh,vim}` — a Vim-side counterpart of
the Neovim harness covering the pure-VimL bindings (header nav,
link nav, `o`/`O` bullet continuation, `<CR>` wrap step). The
LSP-roundtrip bindings (`<C-Space>`, `=`, `-`, …) stay on the Neovim
side because vim-lsp's async layer uses timers that don't fire
inside `vim -e -s` headless mode — their server-side codepath is
already exercised by the Neovim harness and the cargo test suite.

Vim harness covers 12 cases: filetype + 2 command-presence smoke
tests, 4 header-nav (`]]`/`[[`/`]=`/`]u`), `<Tab>` link-nav, `<CR>`
wrap-on-first-press, and 3 bullet-continuation flows.

CI: extended the existing `keymaps` job to install both nvim + vim
and run both harnesses. Verified locally:

  Neovim harness:  19 passed, 0 failed
  Vim harness:     12 passed, 0 failed

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

scripts/test-keymaps-vim.sh

@@ -0,0 +1,60 @@
+#!/usr/bin/env bash
+#
+# scripts/test-keymaps-vim.sh — Vim counterpart of test-keymaps.sh.
+#
+# Pure-VimL portion only. The LSP-roundtrip keymaps (`<C-Space>`,
+# `=`, `-`, …) talk to the server via vim-lsp's timer-driven async
+# layer, which doesn't fire reliably inside `vim -e -s`. Those have
+# Neovim coverage in scripts/test-keymaps.lua, exercising the same
+# Lua command layer + server binary.
+
+set -euo pipefail
+
+REPO_ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+TMP="$(mktemp -d -t nuwiki-keymap-vim-test-XXXXXX)"
+trap 'rm -rf "$TMP"' EXIT
+
+log() { printf '\033[1;34m[keymap-vim]\033[0m %s\n' "$*"; }
+
+if ! command -v vim >/dev/null 2>&1; then
+  log 'vim not installed — skipping'
+  exit 0
+fi
+
+# Don't need the LSP binary for the pure-VimL cases, but make sure
+# the autoload file `expand('<sfile>')` resolves correctly when the
+# script-load-time plugin_root capture runs.
+
+mkdir -p "$TMP/wiki"
+SEED="$TMP/wiki/index.wiki"
+echo "= seed =" > "$SEED"
+
+VIMRC="$TMP/vimrc"
+cat > "$VIMRC" <<EOF
+set nocompatible
+let &runtimepath = '$REPO_ROOT' . ',' . &runtimepath
+filetype plugin indent on
+syntax enable
+" ftdetect/nuwiki.vim already maps *.wiki → vimwiki via \`set filetype\`.
+EOF
+
+RESULTS="$TMP/results.txt"
+
+log "running harness…"
+NUWIKI_KEYMAP_RESULTS="$RESULTS" \
+  vim -e -s -u "$VIMRC" -c "edit $SEED" -c "source $REPO_ROOT/scripts/test-keymaps-vim.vim" \
+    >"$TMP/vim.log" 2>&1 || true
+
+if [[ ! -f "$RESULTS" ]]; then
+  echo 'keymap test harness produced no output' >&2
+  echo '--- vim log ---' >&2
+  cat "$TMP/vim.log" >&2 || true
+  exit 1
+fi
+
+cat "$RESULTS"
+
+if grep -qE '^SUMMARY: [0-9]+ passed, 0 failed' "$RESULTS"; then
+  exit 0
+fi
+exit 1