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/quest.gd

@@ -0,0 +1,33 @@
+class_name Quest
+extends RefCounted
+## An active-quest row. Owns the status enum {active, complete, failed}.
+
+const STATUSES := ["active", "complete", "failed"]
+
+var id: String
+var name: String
+var status: String
+var objective: String
+
+
+func _init(p_id := "", p_name := "", p_status := "active", p_objective := "") -> void:
+	id = p_id
+	name = p_name
+	objective = p_objective
+	set_status(p_status)
+
+
+func set_status(v: String) -> bool:
+	if v not in STATUSES:
+		push_error("invalid quest status: %s" % v)
+		return false
+	status = v
+	return true
+
+
+func to_dict() -> Dictionary:
+	return {"id": id, "name": name, "status": status, "objective": objective}
+
+
+static func from_dict(d: Dictionary) -> Quest:
+	return Quest.new(d.get("id", ""), d.get("name", ""), d.get("status", "active"), d.get("objective", ""))