Update Makefile

- Add 'mithril-client-wasm' compilation in the explorer Makefile
- Add build command with make dev

mithril-explorer/Makefile

@@ -6,6 +6,7 @@ yarn.lock:
 install: yarn.lock
 
 build: yarn.lock
+	make -C ../mithril-client-wasm build
 	yarn && yarn run build
 	# Fix to allow refresh & direct linking to the navigation page on static hosting such as Github Pages
 	# this is because the nextJs router is only active for the home page at start.
@@ -17,7 +18,7 @@ build: yarn.lock
 serve: build
 	yarn run start
 
-dev:
+dev: build
 	@echo "Serving dev build at: http://localhost:3000/explorer"
 	yarn run dev