feat: station_inventory_item migration replacing user_inventory_item

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User Story

As a developer, I need the station_inventory_item table created to replace the old user_inventory_item entity, so that inventory records are backed by the finalized schema with proper catalog and location references.

Background

The existing user_inventory_item entity is incompatible with the finalized schema. It references UexItem via integer uex_item_id, uses a polymorphic location_type/location_uex_id pair, and has no list support. It must be replaced entirely. See docs/schema/inventory-catalog-design.md.

Definition of Done

• Migration creates station_inventory_item table
• Migration drops or renames user_inventory_item table (with data migration plan if needed)
• Old UserInventoryItem entity and related files removed or updated
• UserInventoryModule and OrgInventoryModule updated to use new entity
• All existing inventory API endpoints updated to read/write station_inventory_item
• Unique constraint (owner_type, owner_id, catalog_entry_id, location_id) enforced
• pnpm test passes
• pnpm migration:revert tested

Schema

Column	Type	Nullable	Default	Notes
id	UUID	NO	UUIDv7	PK
owner_type	VARCHAR(10)	NO		user | org | alliance (future)
owner_id	UUID	NO		Polymorphic FK to users or organizations
catalog_entry_id	UUID	NO		FK → station_catalog_entry
location_id	UUID	NO		FK → station_location
quantity	NUMERIC(12,4)	NO	1	Handles SCU fractions and whole unit counts
is_org_available	BOOLEAN	NO	FALSE	User-owned but flagged as available to org
notes	TEXT	YES	NULL
created_at	TIMESTAMPTZ	NO	now()
updated_at	TIMESTAMPTZ	NO	now()

Unique constraint: (owner_type, owner_id, catalog_entry_id, location_id)

Depends on

• feat: station_catalog_entry migration and ETL population from UEX #277 — station_catalog_entry (prerequisite)
• feat: station_location migration and ETL population from discrete location tables #278 — station_location (prerequisite)

Related

• Implement user inventory custom lists #28 — custom lists (depends on this issue)
• Org inventory management UI #29 — org inventory UI (depends on this issue)
• Inventory MVP epic #10 — inventory epic
• docs/schema/inventory-catalog-design.md