Generate the week's Supply run from its plan

Add internal/shopping with Generate(weekStart), one entry point for the
first generation and every regeneration. It builds one group per plan
day (dinner_id, date, position by date) and one item per ingredient of
the dinner's recipe, in ingredient order, reusing the values recipe
grounding stored: a fetched recipe's normalized name with qty and unit
joined for display, or a manual recipe's line as typed with no qty. A
day whose dinner has no recipe or no ingredients gets no group and is
reported in Skipped. Regenerating keeps the id and needed flag of each
item whose (dinner_id, name) is unchanged, matching repeated names in
order; new items are needed and items no longer planned are removed. It
is deterministic and makes no model call. A frozen list is refused.

Migration 0016 makes shopping_lists.title nullable (never empty) so a
list exists untitled until the AI titles it, and adds shopping_groups.date.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

migrations/queries/shopping.sql

@@ -0,0 +1,60 @@
+-- name: GetShoppingList :one
+-- The Supply run of the week starting week_start. Returns sql.ErrNoRows
+-- when there is none.
+SELECT * FROM shopping_lists
+WHERE week_start = ?;
+
+-- name: CreateShoppingList :exec
+-- A new, untitled Supply run: the title is written later, by the AI.
+INSERT INTO shopping_lists (id, week_start, plan_id, status, created_at, updated_at)
+VALUES (?, ?, ?, 'current', ?, ?);
+
+-- name: RegenerateShoppingList :exec
+-- Records a generation of list id from plan plan_id.
+UPDATE shopping_lists
+SET plan_id = ?, updated_at = ?
+WHERE id = ?;
+
+-- name: ListShoppingGroups :many
+-- The groups of list list_id, in list order.
+SELECT * FROM shopping_groups
+WHERE list_id = ?
+ORDER BY position, id;
+
+-- name: ListShoppingItems :many
+-- The items of list list_id with their group's dinner, in list order: by
+-- group, then by item.
+SELECT sqlc.embed(shopping_items), shopping_groups.dinner_id
+FROM shopping_items
+JOIN shopping_groups ON shopping_groups.id = shopping_items.group_id
+WHERE shopping_groups.list_id = ?
+ORDER BY shopping_groups.position, shopping_items.position, shopping_items.id;
+
+-- name: CreateShoppingGroup :exec
+INSERT INTO shopping_groups (id, list_id, dinner_id, date, position, created_at, updated_at)
+VALUES (?, ?, ?, ?, ?, ?, ?);
+
+-- name: MoveShoppingGroup :exec
+UPDATE shopping_groups
+SET position = ?, updated_at = ?
+WHERE id = ?;
+
+-- name: DeleteShoppingGroup :exec
+DELETE FROM shopping_groups
+WHERE id = ?;
+
+-- name: CreateShoppingItem :exec
+-- A new item is needed until the household marks it "have it".
+INSERT INTO shopping_items (id, group_id, name, qty, needed, position, created_at, updated_at)
+VALUES (?, ?, ?, ?, 1, ?, ?, ?);
+
+-- name: MoveShoppingItem :exec
+-- Places item id in group group_id at position with quantity qty; its
+-- name and needed flag are kept.
+UPDATE shopping_items
+SET group_id = ?, qty = ?, position = ?, updated_at = ?
+WHERE id = ?;
+
+-- name: DeleteShoppingItem :exec
+DELETE FROM shopping_items
+WHERE id = ?;