start working on generalizing credential logic

src-tauri/migrations/20240612192956_kv.sql

@@ -0,0 +1,11 @@
+-- key-value store, will be used for various one-off values, serialized to bytes
+CREATE TABLE kv (
+    name TEXT PRIMARY KEY,
+    value BLOB
+);
+
+-- config is currently stored in its own table, as text
+INSERT INTO kv (name, value)
+SELECT 'config', CAST(data AS BLOB) FROM config;
+
+DROP TABLE config;