M1/#292: artist queries (upsert/get/list)

internal/db/queries/artists.sql

@@ -0,0 +1,20 @@
+-- name: UpsertArtist :one
+-- Insert or update by mbid when present; otherwise by (name, sort_name).
+-- Callers pass the canonical sort_name; scanner is responsible for derivation.
+INSERT INTO artists (name, sort_name, mbid)
+VALUES ($1, $2, $3)
+ON CONFLICT (mbid) WHERE mbid IS NOT NULL
+DO UPDATE SET
+    name = EXCLUDED.name,
+    sort_name = EXCLUDED.sort_name,
+    updated_at = now()
+RETURNING *;
+
+-- name: GetArtistByID :one
+SELECT * FROM artists WHERE id = $1;
+
+-- name: GetArtistByName :one
+SELECT * FROM artists WHERE name = $1 LIMIT 1;
+
+-- name: ListArtists :many
+SELECT * FROM artists ORDER BY sort_name;