Add basic configuration module, make it work for title and theme.

src/modules/config.js

@@ -0,0 +1,30 @@
+import { set } from 'vue'
+import StyleSetter from '../services/style_setter/style_setter.js'
+
+const defaultState = {
+  name: 'Pleroma FE'
+}
+
+const config = {
+  state: defaultState,
+  mutations: {
+    setOption (state, { name, value }) {
+      set(state, name, value)
+    }
+  },
+  actions: {
+    setOption ({ commit }, { name, value }) {
+      commit('setOption', {name, value})
+      switch (name) {
+        case 'name':
+          document.title = value
+          break
+        case 'theme':
+          const fullPath = `/static/css/${value}`
+          StyleSetter.setStyle(fullPath)
+      }
+    }
+  }
+}
+
+export default config