start refactoring for default credentials

src-tauri/migrations/20240617142724_credential_split.sql

@@ -42,12 +42,13 @@ CREATE TABLE credentials (
     id BLOB UNIQUE NOT NULL,
     name TEXT UNIQUE NOT NULL,
     type TEXT NOT NULL,
+    is_default BOOLEAN NOT NULL,
     created_at INTEGER NOT NULL
 );
 
 -- populate with basic data from existing AWS credential
-INSERT INTO credentials (id, name, type, created_at)
-SELECT id, 'default', 'aws', created_at FROM aws_tmp;
+INSERT INTO credentials (id, name, type, is_default, created_at)
+SELECT id, 'default', 'aws', 1, created_at FROM aws_tmp;
 
 -- new AWS-specific table
 CREATE TABLE aws_credentials (