Fix smoke test: resolve ApiClient via get_node, defer one frame before first request

Two Godot --script-mode-only quirks, neither a bug in ApiClient itself
(verified working against a real backend, health_check returns 200):
1. Bare autoload identifiers don't resolve at compile time in --script/
   SceneTree runs (the node exists at runtime, root.has_node() is true,
   but referencing it as a plain global name fails to compile) -- use
   get_node() instead.
2. A freshly add_child()'d HTTPRequest isn't reliably "inside tree" yet
   at _initialize() time, since --script mode hasn't processed a frame
   yet -- one process_frame await fixes it.

Verified: full smoke test now passes end-to-end against a live backend
(docker compose postgres + alembic migrations + uvicorn), confirming
ApiClient.health_check() genuinely round-trips.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

scripts/smoke_test_api.gd

@@ -17,8 +17,23 @@ func _initialize() -> void:
 
 
 func _run() -> void:
+	# _initialize() fires before the SceneTree has processed its first frame,
+	# so a freshly add_child()'d HTTPRequest node isn't reliably considered
+	# "inside tree" yet (request_raw fails with !is_inside_tree()). One frame
+	# of delay is enough; this only matters for --script mode, not a real
+	# running game.
+	await process_frame
+
+	# Godot's --script/SceneTree runner doesn't resolve autoload singletons
+	# as bare global identifiers at compile time (the node exists at
+	# runtime -- root.has_node("ApiClient") is true -- but referencing it as
+	# a plain identifier fails with "Identifier not found: ApiClient" during
+	# script compilation). get_node sidesteps compile-time resolution
+	# entirely. This only affects --script mode; a real game scene resolves
+	# the bare autoload name normally.
+	var api_client := root.get_node("ApiClient")
 	print("SMOKE: calling ApiClient.health_check() ...")
-	var result: Dictionary = await ApiClient.health_check()
+	var result: Dictionary = await api_client.health_check()
 	print("SMOKE: result = ", result)
 
 	if result.ok \