fix(db): apply sqlc's actual output for candidate_artist_tags — #2376

Three divergences in the hand-written generated file, all caught by
verify-generate on the first run. Two are sqlc rules I had wrong:

1. When a query's SELECT list exactly matches a table's columns in order,
   sqlc REUSES the model struct rather than emitting a bespoke Row type.
   So ListCandidateArtistTagsForMbids returns []CandidateArtistTag, and
   ListCandidateArtistTagsForMbidsRow should never have existed.

2. models.go is ordered by GO STRUCT NAME, not table name. Table order
   would put candidate_artist_tag_state before candidate_artist_tags;
   sqlc emits CandidateArtistTag before CandidateArtistTagState. The
   earlier slice-3 observation ("ordered by table name") was consistent
   with both orderings and so never discriminated — this case does.

3. sqlc smart-quotes a doubled '' inside a promoted comment into a
   typographic ”. Reworded the prose to say "the empty string" instead of
   encoding a mangling into the source.

Note the integration lane PASSED on the broken push while this failed.
That is #2380's lesson landing again, and the reason the check exists:
valid SQL executing against real Postgres proves nothing about whether
the committed Go matches its source.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

internal/db/dbq/candidate_artist_tags.sql.go

@@ -110,23 +110,17 @@ SELECT candidate_mbid, tag, weight
  WHERE candidate_mbid = ANY($1::text[])
 `
 
-type ListCandidateArtistTagsForMbidsRow struct {
-	CandidateMbid string
-	Tag           string
-	Weight        float64
-}
-
 // Cached tags for a set of candidates, for slice 6's taste-overlap ranking.
 // One row per (candidate, tag).
-func (q *Queries) ListCandidateArtistTagsForMbids(ctx context.Context, dollar_1 []string) ([]ListCandidateArtistTagsForMbidsRow, error) {
+func (q *Queries) ListCandidateArtistTagsForMbids(ctx context.Context, dollar_1 []string) ([]CandidateArtistTag, error) {
 	rows, err := q.db.Query(ctx, listCandidateArtistTagsForMbids, dollar_1)
 	if err != nil {
 		return nil, err
 	}
 	defer rows.Close()
-	var items []ListCandidateArtistTagsForMbidsRow
+	var items []CandidateArtistTag
 	for rows.Next() {
-		var i ListCandidateArtistTagsForMbidsRow
+		var i CandidateArtistTag
 		if err := rows.Scan(&i.CandidateMbid, &i.Tag, &i.Weight); err != nil {
 			return nil, err
 		}
@@ -186,10 +180,11 @@ type ListCandidateArtistsMissingTagsRow struct {
 // Already-in-library candidates are skipped: they have an artists row, so
 // their tags belong in track_tags, and the suggestion query filters them out
 // anyway. $1 = current tag_sources_version, $2 = limit.
-// candidate_name is coalesced to '' so it lands non-nullable in Go: the name is
-// only a Last.fm lookup key, and empty simply means "MBID-keyed providers only",
-// which the provider chain already handles. max() is an arbitrary-but-
-// deterministic pick when several seeds spell the same MBID differently.
+// candidate_name is coalesced to the empty string so it lands non-nullable in
+// Go: the name is only a Last.fm lookup key, and empty simply means "MBID-keyed
+// providers only", which the provider chain already handles. max() is an
+// arbitrary-but-deterministic pick when several seeds spell one MBID
+// differently.
 func (q *Queries) ListCandidateArtistsMissingTags(ctx context.Context, arg ListCandidateArtistsMissingTagsParams) ([]ListCandidateArtistsMissingTagsRow, error) {
 	rows, err := q.db.Query(ctx, listCandidateArtistsMissingTags, arg.TagSourcesVersion, arg.Limit)
 	if err != nil {

internal/db/dbq/models.go

@@ -240,6 +240,12 @@ type AuditLog struct {
 	CreatedAt pgtype.Timestamptz
 }
 
+type CandidateArtistTag struct {
+	CandidateMbid string
+	Tag           string
+	Weight        float64
+}
+
 type CandidateArtistTagState struct {
 	CandidateMbid     string
 	TagSource         string
@@ -247,12 +253,6 @@ type CandidateArtistTagState struct {
 	UpdatedAt         pgtype.Timestamptz
 }
 
-type CandidateArtistTag struct {
-	CandidateMbid string
-	Tag           string
-	Weight        float64
-}
-
 type ContextualLike struct {
 	ID            pgtype.UUID
 	UserID        pgtype.UUID

internal/db/queries/candidate_artist_tags.sql

@@ -20,10 +20,11 @@
 -- Already-in-library candidates are skipped: they have an artists row, so
 -- their tags belong in track_tags, and the suggestion query filters them out
 -- anyway. $1 = current tag_sources_version, $2 = limit.
--- candidate_name is coalesced to '' so it lands non-nullable in Go: the name is
--- only a Last.fm lookup key, and empty simply means "MBID-keyed providers only",
--- which the provider chain already handles. max() is an arbitrary-but-
--- deterministic pick when several seeds spell the same MBID differently.
+-- candidate_name is coalesced to the empty string so it lands non-nullable in
+-- Go: the name is only a Last.fm lookup key, and empty simply means "MBID-keyed
+-- providers only", which the provider chain already handles. max() is an
+-- arbitrary-but-deterministic pick when several seeds spell one MBID
+-- differently.
 SELECT u.candidate_mbid,
        coalesce(max(u.candidate_name), '')::text AS candidate_name,
        sum(u.score)::float8                      AS total_score