feat(backup): full DR bundle export + admin-configurable offsite destinations

Backend-agnostic disaster-recovery backup engine that runs on the current
storage backend (no storage cutover required):

- Full-bundle export: db.dump (pg_dump custom) + every storage blob +
  manifest.json with per-object SHA-256, streamed as a tar. Entry points:
  admin UI download, GET /api/v1/admin/backup/export, scripts/create-full-backup.ts.
- Admin-configurable push destinations (backup_destinations table, migration
  0091): SFTP/SSH, S3-compatible (reuses the minio client), and mounted
  path/NAS behind one transport interface (test/push/prune). Secrets AES-GCM
  at rest; API returns only *IsSet markers.
- Opt-in per-destination AES-256 bundle encryption (scrypt KDF, streamed) +
  scripts/decrypt-backup.ts for restore.
- Wired the previously-dead database-backup cron to runScheduledBackupPush
  (push to enabled destinations, prune to retention, alert super-admins on
  failure).

Tests: 1608 unit/integration pass; tsc + lint clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/lib/storage/migrate.ts

@@ -136,7 +136,7 @@ async function markRowMigrated(
   `);
 }
 
-interface RowRef {
+export interface RowRef {
   tableName: string;
   pk: string;
   key: string;
@@ -164,6 +164,22 @@ async function listKeysFor(tbl: StorageKeyTable): Promise<RowRef[]> {
   }));
 }
 
+/**
+ * Inventory every blob reference across all blob-bearing tables. Used by the
+ * full-backup exporter (Phase 4a) to enumerate what to bundle. `excludeTables`
+ * lets the exporter drop `backup_jobs` so a full export doesn't recursively
+ * include prior backup artefacts.
+ */
+export async function collectStorageRefs(opts?: { excludeTables?: string[] }): Promise<RowRef[]> {
+  const exclude = new Set(opts?.excludeTables ?? []);
+  const all: RowRef[] = [];
+  for (const tbl of TABLES_WITH_STORAGE_KEYS) {
+    if (exclude.has(tbl.table)) continue;
+    all.push(...(await listKeysFor(tbl)));
+  }
+  return all;
+}
+
 // ─── streaming + sha256 verify ──────────────────────────────────────────────
 
 /**