tests: compare pqcli with upstream in node

`just test` now fetches Progress Quest web's game logic from the public
site into $XDG_CACHE_HOME/pqcli/pq-web, pinned by SHA-256 so a change on
the site fails loudly. Nothing from upstream is committed.

tests/upstream/harness.js runs that code headless. test_upstream.py
checks the word lists, MonsterTask and the other generators from 200
generator states, and three whole games of 10000 tasks each, comparing
all state including the generator after every task. Without node or the
fetched files, these tests are skipped.

justfile

@@ -16,8 +16,12 @@ basic *args:
 lint:
     uv run prek run -a
 
+# Download Progress Quest web's game logic for the upstream tests
+fetch-upstream:
+    uv run python tests/upstream/fetch.py
+
 # Run the test suite; extra arguments go to pytest
-test *args:
+test *args: fetch-upstream
     uv run pytest {{args}}
 
 # Re-record the gameplay parity fixtures (only when gameplay should change)