refactor(db): collapse repository rollout scaffolding into single factory

Repositories are now the only data path. Replaces the 41 current-*-repository
wrapper files, the DATABASE_LAYER_REPOSITORY_ROLLOUT flag/alias map and the
unused database/runtime adapter with repositories/factory.ts, a plain
DatabaseContext type and an in-memory TestSqliteDatabase test harness.

src/backend/ssh/tmux-monitor.ts

@@ -4,8 +4,10 @@ import { Client, type ConnectConfig } from "ssh2";
 import { createCorsMiddleware } from "../utils/cors-config.js";
 import { AuthManager } from "../utils/auth-manager.js";
 import { DataCrypto } from "../utils/data-crypto.js";
-import { createCurrentTmuxSessionTagRepository } from "../database/repositories/current-tmux-session-tag-repository.js";
-import { createCurrentUserRepository } from "../database/repositories/current-user-repository.js";
+import {
+  createCurrentTmuxSessionTagRepository,
+  createCurrentUserRepository,
+} from "../database/repositories/factory.js";
 import { logAudit, getRequestMeta } from "../utils/audit-logger.js";
 import { sshLogger } from "../utils/logger.js";
 import { SSH_ALGORITHMS } from "../utils/ssh-algorithms.js";