feat: web frontend; middleware; serde (WIP?)

migrations/20251130140000_add_admin_auth.sql

@@ -0,0 +1,3 @@
+-- Add admin authentication
+INSERT OR IGNORE INTO config (key, value, description) VALUES
+    ('admin_password_hash', '$2a$12$foWbCgnovjZxmfE1fbut9uJlMCWrx.KrGUbmKlDH727B4JB7YUZEe', 'Admin password hash (default: admin123)');