First commit. Lot to do...

users.py

@@ -0,0 +1,59 @@
+import json
+
+USER_FILE = "./data/users.json"
+
+def load_users():
+    try:
+        with open(USER_FILE, "r") as f:
+            return json.load(f)
+    except FileNotFoundError:
+        return {}
+
+def save_users(data):
+    with open(USER_FILE, "w") as f:
+        json.dump(data, f)
+
+def update_user(user_id, username, fullname):
+    has_changes = False
+    users = load_users()
+    user = users.get(str(user_id), {})
+    
+    if user.get("username", "") != username:
+        has_changes = True
+        user["username"] = username
+    if user.get("fullname", "") != fullname:
+        has_changes = True
+        user["fullname"] = fullname
+    if not user.get("role"):
+        has_changes = True
+        user["role"] = "guest"
+    
+    if has_changes:
+        users[str(user_id)] = user
+        save_users(users)
+
+
+def get_role(user_id):
+    return load_users().get(str(user_id), {}).get("role", "guest")
+
+def set_credentials(user_id, username, password):
+    users = load_users()
+    user = users.get(str(user_id), {})
+    user["credentials"] = {"username": username, "password": password}
+    users[str(user_id)] = user
+    save_users(users)
+
+def get_credentials(user_id):
+    return load_users().get(str(user_id), {}).get("credentials")
+
+def get_grantor_credentials(user_id, gate):
+    from access_control import load_access
+    access = load_access().get(str(user_id), {})
+    entry = access.get(gate) or access.get("all")
+    if not entry:
+        return None
+    grantor_id = entry.get("grantor")
+    return get_credentials(grantor_id)
+
+def get_admins():
+    return [uid for uid, u in load_users().items() if u.get("role") == "admin"]