feat(gems): add multiplayer gem game with custom content packs

- implement FastAPI and HTMX lobby and game interfaces
- support up to four human and AI-controlled players
- add configurable rules, victory conditions, and expansion modules
- support validated JSON cards, patrons, objectives, and outposts

tests/gems/test_content.py

@@ -0,0 +1,45 @@
+from __future__ import annotations
+
+import json
+
+import pytest
+
+from python.gems.content import ContentPackError, content_pack_schema, parse_content_pack
+
+
+def test_schema_uses_neutral_patrons_name() -> None:
+    assert "patrons" in content_pack_schema()["properties"]
+    assert "governors" not in content_pack_schema()["properties"]
+
+
+def test_governors_is_accepted_as_input_alias(content_pack) -> None:
+    data = content_pack.model_dump(mode="json")
+    data["governors"] = data.pop("patrons")
+    parsed = parse_content_pack(json.dumps(data))
+    assert parsed.pack.patrons[0].id == "patron_one"
+
+
+def test_both_patron_names_are_rejected(content_pack) -> None:
+    data = content_pack.model_dump(mode="json")
+    data["governors"] = data["patrons"]
+    with pytest.raises(ContentPackError, match="use patrons or governors"):
+        parse_content_pack(json.dumps(data))
+
+
+def test_standard_symbols_are_normalized_in_canonical_pack_data(content_pack) -> None:
+    data = content_pack.model_dump(mode="json")
+    data["resources"][0].update(label="Onyx", symbol="B")
+    data["wild_resource"].update(label="Gold", symbol="Au")
+
+    parsed = parse_content_pack(json.dumps(data))
+    canonical = json.loads(parsed.canonical_json)
+
+    assert canonical["resources"][0]["symbol"] == "O"
+    assert canonical["wild_resource"]["symbol"] == "G"
+
+
+def test_unknown_resource_reference_is_rejected(content_pack) -> None:
+    data = content_pack.model_dump(mode="json")
+    data["cards"][0]["cost"] = {"missing": 1}
+    with pytest.raises(ContentPackError, match="unknown cost resource"):
+        parse_content_pack(json.dumps(data))