parity(2): insert-mode list bindings (<C-D>/<C-T>/<C-L><C-?>)

Match upstream vimwiki's insert-mode list editing:
  <C-D>      list_change_level(-1)   dedent current item
  <C-T>      list_change_level(+1)   indent current item
  <C-L><C-J> list_cycle_symbol(+1)   cycle marker forward
  <C-L><C-K> list_cycle_symbol(-1)   cycle marker backward
  <C-L><C-M> list_toggle_or_add_chk  toggle if has checkbox, else add `[ ]`

Cycle order matches vimwiki's canonical run:
  - → * → # → 1. → 1) → a) → A) → i) → I) → (wrap)

Both Lua and VimL paths wired. Lua callbacks fire directly (no `<C-o>`
dance) since list_change_level / changeSymbol mutate the buffer via
the LSP applyEdit pipeline, which works cleanly in insert mode. VimL
keeps the `<C-o>:call …<CR>` idiom since that's the standard there.

Harness adds 5 cases covering the new insert-mode bindings plus one
direct LSP roundtrip for changeSymbol — surfaced a long-standing
stale-binary footgun in test-keymaps.sh (rebuilt only when bin was
missing; now rebuilds every run since incremental cargo is fast).
Harness also captures server log_messages and dumps them on failure
so future swallowed-error bugs (Err → log + Ok(None)) are visible.

Gates: 421 Rust / 25 Neovim / 12 Vim.

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

scripts/test-keymaps.sh

@@ -20,14 +20,15 @@ trap 'rm -rf "$TMP"' EXIT
 
 log() { printf '\033[1;34m[keymap-test]\033[0m %s\n' "$*"; }
 
-# Build the LSP binary if missing.
+# Always rebuild the LSP binary so harness runs against current sources.
+# A previous version only built when the symlink was missing, which let
+# stale binaries pass tests against unrelated code — incremental cargo
+# build is fast, so just always run it.
 BIN="$REPO_ROOT/bin/nuwiki-ls"
-if [[ ! -x "$BIN" ]]; then
-  log 'building nuwiki-ls (release)…'
-  cargo build --release -p nuwiki-ls --manifest-path "$REPO_ROOT/Cargo.toml" >/dev/null
-  mkdir -p "$REPO_ROOT/bin"
-  ln -sf "$REPO_ROOT/target/release/nuwiki-ls" "$BIN"
-fi
+log 'building nuwiki-ls (release, incremental)…'
+cargo build --release -p nuwiki-ls --manifest-path "$REPO_ROOT/Cargo.toml" >/dev/null
+mkdir -p "$REPO_ROOT/bin"
+ln -sf "$REPO_ROOT/target/release/nuwiki-ls" "$BIN"
 
 mkdir -p "$TMP/wiki"
 echo "= seed =" > "$TMP/wiki/index.wiki"