fix(client): make game depends on full build, use --import for client

build-client used --quit without --import, which failed to create
.godot/ and register class_name types after a clean. game target
only depended on build-server, skipping client entirely. clean now
preserves the .godot/ directory itself while clearing contents.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Makefile

@@ -86,7 +86,7 @@ build-server:
 
 build-client:
 	@test -n "$(GODOT)" || { echo "Godot not found. Run 'make setup' first."; exit 1; }
-	$(GODOT) --headless --path client --quit
+	$(GODOT) --headless --path client --import --quit
 
 # --- Run ---
 
@@ -97,7 +97,7 @@ client:
 	@test -n "$(GODOT)" || { echo "Godot not found. Run 'make setup' first."; exit 1; }
 	$(GODOT) --path client
 
-game: stop build-server
+game: stop build
 	@test -n "$(GODOT)" || { echo "Godot not found. Run 'make setup' first."; exit 1; }
 	@echo "Starting server..."
 	@cd server && cargo run &
@@ -289,5 +289,5 @@ content-ron:
 clean:
 	cd server && cargo clean || true
 	rm -rf .cache/*
-	rm -rf client/.godot client/reports
+	rm -rf client/.godot/* client/reports
 	@echo "Clean complete."