fix(check): fail when the manifest is behind the tag, not merely different

`task check` asserted plugin.json's version EQUALS the latest tag. `git
describe` is local-only, so any checkout that had not fetched the tag CI just
pushed went red on a commit that was correct — three times in one backlog
session, on the loop push → CI tags and pushes the bump → pull → red until you
also fetch tags.

The fault the assertion exists for is the manifest failing to move: a release
whose manifest still names the old version, so no installed host ever sees the
update. That is manifest < tag. Ahead is normal and is now quiet.

Ordering needed a real comparison, and bin/doctor had already grown one for
#30, so it moves to bin/newer-version with its own tests rather than existing
twice. Seven cases including the lexical trap (0.8.10 beats 0.8.9) and a
missing component counting as zero.

Verified by mutation: manifest 0.1.0 against tag v0.9.0 exits 201 naming both
versions; manifest 9.9.9 exits 0; the real tree exits 0.

Closes #34
Bump-Type: patch

Taskfile.yml

@@ -104,8 +104,14 @@ tasks:
         if [ -f '{{.PLUGIN_MANIFEST}}' ]; then
           manifest_v=$(sed -n 's/.*"version"[[:space:]]*:[[:space:]]*"\([^"]*\)".*/\1/p' '{{.PLUGIN_MANIFEST}}' | head -1)
           tag_v=$(git -C '{{.TASKFILE_DIR}}' describe --tags --abbrev=0 2>/dev/null | sed 's/^v//' || echo '')
-          if [ -n "$tag_v" ] && [ "$manifest_v" != "$tag_v" ]; then
-            echo "ERROR: plugin.json version ($manifest_v) != latest tag ($tag_v)" >&2
+          # Ordering, not equality. The fault this guards is the manifest
+          # failing to MOVE — a release tag whose manifest still names the old
+          # version, so no installed host ever sees the update. A manifest
+          # ahead of the newest tag this checkout knows about is the normal
+          # state between the tagger's bump commit and a tag fetch (#34).
+          if [ -n "$tag_v" ] && [ "$manifest_v" != "$tag_v" ] \
+             && [ "$(sh '{{.TASKFILE_DIR}}/bin/newer-version' "$manifest_v" "$tag_v")" = "$tag_v" ]; then
+            echo "ERROR: plugin.json version ($manifest_v) is behind the latest tag ($tag_v) — installed hosts never see the update" >&2
             fail=1
           fi
         else