FRE-608: Add Turso database setup with Drizzle ORM

- Create schema for users, projects, scripts, characters, scenes, revisions
- Implement DatabaseManager with connection pooling
- Implement EdgeDatabaseManager for multi-region replicas
- Implement DatabaseBackupManager with automated scheduling
- Generate initial migration with 9 tables
- Add seed script and documentation
- Configure Drizzle Kit for migration management
- Add NPM scripts for database operations

Co-Authored-By: Paperclip <noreply@paperclip.ing>

drizzle.config.ts

@@ -0,0 +1,11 @@
+import { defineConfig } from "drizzle-kit";
+
+export default defineConfig({
+  schema: "./src/db/schema/index.ts",
+  out: "./src/db/migrations",
+  dialect: "turso",
+  dbCredentials: {
+    url: process.env.TURSO_DATABASE_URL!,
+    authToken: process.env.TURSO_AUTH_TOKEN!,
+  },
+});