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/log_player.gd

@@ -0,0 +1,33 @@
+class_name LogPlayer
+extends RefCounted
+## A canon-log player row. Carries ONLY name, class_id, luck_descriptor (§7):
+## no numeric Luck, no stats — those live in GameState and never reach the AI.
+
+const CLASSES := ["sellsword", "assassin", "priest"]
+
+var name: String
+var class_id: String
+var luck_descriptor: String
+
+
+func _init(p_name := "", p_class_id := "", p_luck_descriptor := "") -> void:
+	name = p_name
+	luck_descriptor = p_luck_descriptor
+	if p_class_id != "":
+		set_class_id(p_class_id)
+
+
+func set_class_id(v: String) -> bool:
+	if v not in CLASSES:
+		push_error("invalid class_id: %s" % v)
+		return false
+	class_id = v
+	return true
+
+
+func to_dict() -> Dictionary:
+	return {"name": name, "class_id": class_id, "luck_descriptor": luck_descriptor}
+
+
+static func from_dict(d: Dictionary) -> LogPlayer:
+	return LogPlayer.new(d.get("name", ""), d.get("class_id", ""), d.get("luck_descriptor", ""))