feat(client): id helper + leaf canon-log entities with owned invariants

Also configure GUT to not treat push_error() as a test failure
(client/.gutconfig.json: failure_error_types = [engine, gut]).
The brief's LogPlayer/Quest setters intentionally push_error() on
rejected input; GUT's default failure_error_types includes
push_error, which would fail test_player_rejects_unknown_class and
test_quest_status_enum despite their assertions passing.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

client/scripts/canon_log/party_member.gd

@@ -0,0 +1,25 @@
+class_name PartyMember
+extends RefCounted
+## A companion row. Owns the disposition clamp (−100..100, charter §9).
+
+var id: String
+var name: String
+var disposition: int
+
+
+func _init(p_id := "", p_name := "", p_disposition := 0) -> void:
+	id = p_id
+	name = p_name
+	set_disposition(p_disposition)
+
+
+func set_disposition(v: int) -> void:
+	disposition = clampi(v, -100, 100)
+
+
+func to_dict() -> Dictionary:
+	return {"id": id, "name": name, "disposition": disposition}
+
+
+static func from_dict(d: Dictionary) -> PartyMember:
+	return PartyMember.new(d.get("id", ""), d.get("name", ""), int(d.get("disposition", 0)))