feat(warehouses): track physical container stack and slot positions

Extends the warehouse hierarchy below zone with ground stacks and vertical
slots, so a container's exact position is recorded rather than only its zone.

- freight.warehouse_zone_stacks / warehouse_zone_slots, plus nullable
  stack_id / slot_id on warehouse_inventory (existing rows stay valid)
- slot occupancy is derived from inventory status, guarded by a partial
  unique index, so no exit path has to remember to free a slot
- placement service: hierarchy validation, bottom-up stacking rules,
  accessibility/blocking-container reads, capacity vs slot summaries
- stack CRUD with auto-generated slots; reuses warehouse-zone permissions
- slot support folded into the existing move()/store() paths
- fix: validateLocation now rejects a mismatched warehouse/yard/zone triple
- seed:warehouse-layout builds the layout from a JSON config

apps/edr-freight-api/src/modules/warehouses/dto/move-inventory.dto.ts

@@ -14,6 +14,14 @@ export class MoveInventoryDto {
   @IsUUID()
   zoneId!: string;
 
+  @ApiPropertyOptional({
+    format: 'uuid',
+    description: 'Exact physical slot in the destination zone. Container yards only.',
+  })
+  @IsOptional()
+  @IsUUID()
+  slotId?: string;
+
   @ApiPropertyOptional()
   @IsOptional()
   @IsString()

apps/edr-freight-api/src/modules/warehouses/dto/placement.dto.ts

@@ -0,0 +1,33 @@
+import { ApiProperty, ApiPropertyOptional } from '@nestjs/swagger';
+import { IsIn, IsOptional, IsUUID } from 'class-validator';
+
+export class FindAvailableSlotDto {
+  @ApiProperty({ format: 'uuid' })
+  @IsUUID()
+  yardId!: string;
+
+  @ApiPropertyOptional({ format: 'uuid', description: 'Narrow the search to one zone.' })
+  @IsOptional()
+  @IsUUID()
+  zoneId?: string;
+
+  @ApiPropertyOptional({ enum: ['IMPORT', 'EXPORT', 'BOTH'], description: 'Null/BOTH matches any yard direction.' })
+  @IsOptional()
+  @IsIn(['IMPORT', 'EXPORT', 'BOTH'])
+  direction?: string;
+
+  @ApiPropertyOptional({ format: 'uuid' })
+  @IsOptional()
+  @IsUUID()
+  cargoTypeId?: string;
+}
+
+export class AssignSlotDto {
+  @ApiPropertyOptional({
+    format: 'uuid',
+    description: 'Target slot. Omit to let the placement engine pick the lowest free level.',
+  })
+  @IsOptional()
+  @IsUUID()
+  slotId?: string;
+}

apps/edr-freight-api/src/modules/warehouses/dto/store-inventory.dto.ts

@@ -22,6 +22,15 @@ export class StoreInventoryDto {
   @IsUUID()
   zoneId?: string;
 
+  @ApiPropertyOptional({
+    format: 'uuid',
+    description:
+      'Exact physical slot. Container yards only; omit to let the placement engine pick the lowest free level.',
+  })
+  @IsOptional()
+  @IsUUID()
+  slotId?: string;
+
   @ApiPropertyOptional()
   @IsOptional()
   @IsString()

apps/edr-freight-api/src/modules/warehouses/dto/warehouse-zone-stack.dto.ts

@@ -0,0 +1,120 @@
+import { ApiProperty, ApiPropertyOptional } from '@nestjs/swagger';
+import { IsBoolean, IsEnum, IsInt, IsOptional, IsString, IsUUID, Max, MaxLength, Min } from 'class-validator';
+
+import {
+  DEFAULT_MAX_STACK_HEIGHT,
+  WAREHOUSE_ZONE_STACK_STATUSES,
+  WarehouseZoneStackStatus,
+} from '../entities/warehouse-zone-stack.entity';
+import {
+  WAREHOUSE_ZONE_SLOT_STATUSES,
+  WarehouseZoneSlotStatus,
+} from '../entities/warehouse-zone-slot.entity';
+
+/** Nobody stacks boxes this high; the cap is here to catch a typo'd 30. */
+const MAX_SUPPORTED_STACK_HEIGHT = 10;
+
+export class CreateWarehouseZoneStackDto {
+  @ApiPropertyOptional({ format: 'uuid', description: 'Optional — taken from the route param when omitted' })
+  @IsOptional()
+  @IsUUID()
+  zoneId?: string;
+
+  @ApiProperty({ example: 'ZA-001' })
+  @IsString()
+  @MaxLength(40)
+  code!: string;
+
+  @ApiPropertyOptional()
+  @IsOptional()
+  @IsString()
+  @MaxLength(160)
+  name?: string;
+
+  @ApiPropertyOptional({ description: 'Physical row label' })
+  @IsOptional()
+  @IsString()
+  @MaxLength(20)
+  row?: string;
+
+  @ApiPropertyOptional({ description: 'Physical bay label' })
+  @IsOptional()
+  @IsString()
+  @MaxLength(20)
+  bay?: string;
+
+  @ApiPropertyOptional({ description: 'Physical position label' })
+  @IsOptional()
+  @IsString()
+  @MaxLength(20)
+  position?: string;
+
+  @ApiPropertyOptional({
+    default: DEFAULT_MAX_STACK_HEIGHT,
+    description: 'One slot is generated per level, 1 to this height.',
+  })
+  @IsOptional()
+  @IsInt()
+  @Min(1)
+  @Max(MAX_SUPPORTED_STACK_HEIGHT)
+  maxStackHeight?: number;
+}
+
+export class UpdateWarehouseZoneStackDto {
+  @ApiPropertyOptional()
+  @IsOptional()
+  @IsString()
+  @MaxLength(40)
+  code?: string;
+
+  @ApiPropertyOptional()
+  @IsOptional()
+  @IsString()
+  @MaxLength(160)
+  name?: string;
+
+  @ApiPropertyOptional()
+  @IsOptional()
+  @IsString()
+  @MaxLength(20)
+  row?: string;
+
+  @ApiPropertyOptional()
+  @IsOptional()
+  @IsString()
+  @MaxLength(20)
+  bay?: string;
+
+  @ApiPropertyOptional()
+  @IsOptional()
+  @IsString()
+  @MaxLength(20)
+  position?: string;
+
+  @ApiPropertyOptional({ description: 'Raising it adds slots; lowering it removes the empty top levels.' })
+  @IsOptional()
+  @IsInt()
+  @Min(1)
+  @Max(MAX_SUPPORTED_STACK_HEIGHT)
+  maxStackHeight?: number;
+
+  @ApiPropertyOptional({ enum: WAREHOUSE_ZONE_STACK_STATUSES })
+  @IsOptional()
+  @IsEnum(WAREHOUSE_ZONE_STACK_STATUSES)
+  status?: WarehouseZoneStackStatus;
+}
+
+export class UpdateWarehouseZoneSlotDto {
+  @ApiPropertyOptional({
+    enum: WAREHOUSE_ZONE_SLOT_STATUSES,
+    description: 'Operator intent only. OCCUPIED is derived from inventory and cannot be set here.',
+  })
+  @IsOptional()
+  @IsEnum(WAREHOUSE_ZONE_SLOT_STATUSES)
+  status?: WarehouseZoneSlotStatus;
+
+  @ApiPropertyOptional()
+  @IsOptional()
+  @IsBoolean()
+  isActive?: boolean;
+}