refactor: refactor for modern layout

- split frontend and backend.
- update backend with modern Python dev strategies.

frontend/static/js/localStorageAssist.js

@@ -0,0 +1,21 @@
+function ccn_localstorageAssist_Get(index, defaultValue) {
+    var cache = localStorage.getItem(index);
+    if (cache == null) {
+        ccn_localstorageAssist_Set(index, defaultValue);
+        return defaultValue;
+    } else return cache;
+}
+
+function ccn_localstorageAssist_Set(index, value) {
+    localStorage.setItem(index, value);
+}
+
+// =================================== seperated data getter setter
+
+function ccn_localstorageAssist_GetApiToken() {
+    return ccn_localstorageAssist_Get('ccn-token', '');
+}
+
+function ccn_localstorageAssist_SetApiToken(value) {
+    ccn_localstorageAssist_Set('ccn-token', value);
+}