feat: add shelve management functionality

db/queries/shelve.sql

@@ -0,0 +1,31 @@
+-- name: GetShelveByID :one
+SELECT * FROM shelves
+WHERE id = sqlc.arg(id);
+
+-- name: ListShelves :many
+SELECT * FROM shelves
+ORDER BY created_at DESC;
+
+-- name: CreateShelve :one
+INSERT INTO shelves (cabinet_id,name,level_index, description, created_at)
+VALUES (
+    sqlc.arg(cabinet_id),
+    sqlc.arg(name),
+    sqlc.arg(level_index),
+    sqlc.arg(description),
+    sqlc.arg(created_at)
+)
+RETURNING *;
+
+-- name: UpdateShelve :one
+UPDATE shelves
+SET name = CASE WHEN sqlc.arg(name) = '' THEN name ELSE sqlc.arg(name) END,
+    level_index = CASE WHEN sqlc.arg(level_index) = 0 THEN level_index ELSE sqlc.arg(level_index) END,
+    description = coalesce(sqlc.arg(description), description),
+    updated_at = sqlc.arg(updated_at)
+WHERE id = sqlc.arg(id)
+RETURNING *;
+
+-- name: DeleteShelve :execrows
+DELETE FROM shelves
+WHERE id = sqlc.arg(id);