feat(exports): dataset-driven table export, starting with bookings

Adds a parallel export system the reports module can also draw on. A dataset
describes a table's exportable fields — including related-entity detail the
list page never shows — and the engine assembles a query from whichever fields
the caller picked.

GET /exports                 catalog (metadata only; select/requires never ship)
GET /exports/:key/count      exact row count + per-format caps
GET /exports/:key/download   csv | xlsx | pdf

Two invariants carry the design:

- Every lazy join is a LEFT join, and ExportJoin has no 'kind' field to make
  anything else expressible. An inner join added because a checkbox was ticked
  would change the rowset, so two exports of the same filters would disagree on
  their row count.
- Because of that, the count cannot depend on field selection, so /count runs
  base + alwaysJoin only and is exact rather than an estimate. Verified: count
  and the delivered file both report 223 rows.

One-to-many relations (a booking's containers) aggregate in a correlated
subquery rather than joining, so a row can never multiply.

Export rides each dataset's existing view permission — no new permission keys
and no seeder change. Sensitive columns are simply never declared as fields:
raw gateway payloads, signature blobs, error dumps, raw jsonb snapshots,
internal user UUIDs and review notes are all absent by construction.

bookings ships 77 fields across 10 groups. scripts/validate-export-datasets.ts
EXPLAINs every dataset's widest query, its count query, and each field on its
own against the real database — the per-field pass is what catches a field
referencing a join it forgot to declare, which otherwise only fails when that
one field is picked alone.

apps/edr-freight-api/src/app.module.ts

@@ -100,6 +100,7 @@ import { RoutesModule } from "./modules/routes/routes.module";
 import { WarehousesModule } from "./modules/warehouses/warehouses.module";
 import { OverviewModule } from "./modules/overview/overview.module";
 import { ReportsModule } from "./modules/reports/reports.module";
+import { ExportsModule } from "./modules/exports/exports.module";
 import { UserTradeAccessModule } from "./modules/user-trade-access/user-trade-access.module";
 import { VehiclesModule } from "./modules/vehicles/vehicles.module";
 import { DriversModule } from "./modules/drivers/drivers.module";
@@ -234,6 +235,7 @@ if (!process.env.APPLICATION_NAME) {
     WarehousesModule,
     OverviewModule,
     ReportsModule,
+    ExportsModule,
     UserTradeAccessModule,
     VehiclesModule,
     DriversModule,