Complete bootstrap base frontend prototype.

- login page and playlist setting page frontend templates.
- fast API route.
- reading and saving config files
- mock login logic for UI interaction demo

app/utils/config.py

@@ -0,0 +1,14 @@
+import json
+import os
+
+CONFIG_PATH = os.path.join(os.path.dirname(__file__), "..", "config.json")
+
+def load_config():
+    if not os.path.exists(CONFIG_PATH):
+        return {}
+    with open(CONFIG_PATH, "r", encoding="utf-8") as f:
+        return json.load(f)
+
+def save_config(new_config):
+    with open(CONFIG_PATH, "w", encoding="utf-8") as f:
+        json.dump(new_config, f, indent=4, ensure_ascii=False)