feat(fase-5.10.0): drop shopping_items.unit column

The unit field had no edit path under the redesign (only name + qty
remain in the row; the double-tap overlay is name-only). Users can encode
the unit inside the name when it matters — e.g. "Milk 1L", "Eggs 1 doz".

Changes
  supabase/migrations/011_drop_shopping_items_unit.sql — DROP COLUMN
  supabase/seed.sql — unit values folded into names where relevant
  supabase/tests/002_item_frequency_trigger.sql — remove unit from INSERT
  packages/types — remove unit from ShoppingItem Row/Insert/Update
  apps/web/src/lib/stores/lists.ts — addItem/updateItem signatures
  apps/web/src/routes/(app)/lists/[id]/+page.svelte — purge newUnit /
    editUnit state + inputs + display
  apps/web/src/routes/(app)/lists/[id]/session/+page.svelte — simplify
    quantity-only render
  apps/web/messages/{en,es}.json — remove list_unit_label

Verification
  just test-db  → 34 pgTAP green
  just test-integration → 140 + 2 skipped
  just test-unit → 11 green
  just test-e2e → 39 + 2 skipped

The generated search tsvector on shopping_items.search already indexes
only `name`, so full-text search coverage is unchanged.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/web/src/lib/stores/lists.ts

@@ -150,7 +150,6 @@ export async function addItem(
 	listId: string,
 	name: string,
 	quantity: number | null,
-	unit: string | null,
 	userId: string,
 	sortOrder: number,
 	id?: string
@@ -160,7 +159,6 @@ export async function addItem(
 		list_id: listId,
 		name,
 		quantity,
-		unit,
 		sort_order: sortOrder,
 		created_by: userId
 	};
@@ -180,7 +178,7 @@ export async function updateItem(
 	patch: Partial<
 		Pick<
 			ShoppingItem,
-			'name' | 'quantity' | 'unit' | 'is_checked' | 'checked_by' | 'checked_at' | 'sort_order'
+			'name' | 'quantity' | 'is_checked' | 'checked_by' | 'checked_at' | 'sort_order'
 		>
 	>
 ) {