feat: add admin + provider_configs migration

k-tv-backend/migrations_sqlite/20260318000000_add_admin_and_provider_configs.sql

@@ -0,0 +1,8 @@
+ALTER TABLE users ADD COLUMN is_admin INTEGER NOT NULL DEFAULT 0;
+
+CREATE TABLE provider_configs (
+  provider_type TEXT PRIMARY KEY,
+  config_json   TEXT NOT NULL,
+  enabled       INTEGER NOT NULL DEFAULT 1,
+  updated_at    TEXT NOT NULL
+);