Add Turso/Vercel deployment configuration

- Updated database connection to support Turso auth token
- Added vercel.json with bun build configuration
- Updated environment schema for production deployment
- Added new features and components for production readiness

drizzle/0001_yielding_dormammu.sql

@@ -0,0 +1,2 @@
+ALTER TABLE `beenvoice_invoice` ADD COLUMN `taxRate` real NOT NULL DEFAULT 0;
+UPDATE `beenvoice_invoice` SET `taxRate` = 0 WHERE `taxRate` IS NULL;