feat: add feature based structure

internal/author/query.sql

@@ -0,0 +1,26 @@
+-- name: GetAuthor :one
+SELECT * FROM authors
+WHERE id = $1 LIMIT 1;
+
+-- name: ListAuthors :many
+SELECT * FROM authors
+ORDER BY name;
+
+-- name: CreateAuthor :one
+INSERT INTO authors (
+  name, bio
+) VALUES (
+  $1, $2
+)
+RETURNING *;
+
+-- name: UpdateAuthor :exec
+UPDATE authors
+  set name = $2,
+  bio = $3
+WHERE id = $1
+RETURNING *;
+
+-- name: DeleteAuthor :exec
+DELETE FROM authors
+WHERE id = $1;