db: split runtime facade by domain

src/db/runtime-database.ts

@@ -0,0 +1,34 @@
+import { Database } from 'bun:sqlite';
+
+import {
+  openInitializedDatabaseFromFile,
+  openInitializedInMemoryDatabase,
+  openInitializedPersistentDatabase,
+} from './database-lifecycle.js';
+
+let db: Database | undefined;
+
+export function initDatabase(): void {
+  db = openInitializedPersistentDatabase();
+}
+
+/** @internal - for tests only. Creates a fresh in-memory database. */
+export function _initTestDatabase(): void {
+  db = openInitializedInMemoryDatabase();
+}
+
+/** @internal - for tests only. Opens an existing database file and runs schema/migrations. */
+export function _initTestDatabaseFromFile(dbPath: string): void {
+  db = openInitializedDatabaseFromFile(dbPath);
+}
+
+export function requireDatabase(): Database {
+  if (!db) {
+    throw new Error('Database not initialized');
+  }
+  return db;
+}
+
+export function getDatabaseIfInitialized(): Database | undefined {
+  return db;
+}