Change genre.Put() to upsert. Fix #1918 and #1564 (#1920)

* persistence/genre: change Put() to upsert

Absolutely disgusting hack to work around [1]. Try to insert the genre,
but if it conflicts, ignore it and update the genre with the existing
ID.

[1]: https://github.com/navidrome/navidrome/issues/1918.

* scanner: remove cached genre repository

Not needed anytmore. And remember:

  "Many Small Queries Are Efficient In SQLite" [1].

[1]: https://www.sqlite.org/np1queryprob.html

* Revert "scanner: remove cached genre repository"

This reverts commit c5d900aa43e1c86b69f923b408e11ab8df8d815c.

* Use squirrel to build SQL, to reduce risk of SQL injection

Co-authored-by: Deluan <deluan@navidrome.org>

persistence/genre_repository_test.go

@@ -4,6 +4,7 @@ import (
 	"context"
 
 	"github.com/beego/beego/v2/client/orm"
+	"github.com/google/uuid"
 	"github.com/navidrome/navidrome/log"
 	"github.com/navidrome/navidrome/model"
 	"github.com/navidrome/navidrome/persistence"
@@ -18,12 +19,39 @@ var _ = Describe("GenreRepository", func() {
 		repo = persistence.NewGenreRepository(log.NewContext(context.TODO()), orm.NewOrm())
 	})
 
-	It("returns all records", func() {
-		genres, err := repo.GetAll()
-		Expect(err).To(BeNil())
-		Expect(genres).To(ConsistOf(
-			model.Genre{ID: "gn-1", Name: "Electronic", AlbumCount: 1, SongCount: 2},
-			model.Genre{ID: "gn-2", Name: "Rock", AlbumCount: 3, SongCount: 3},
-		))
+	Describe("GetAll()", func() {
+		It("returns all records", func() {
+			genres, err := repo.GetAll()
+			Expect(err).To(BeNil())
+			Expect(genres).To(ConsistOf(
+				model.Genre{ID: "gn-1", Name: "Electronic", AlbumCount: 1, SongCount: 2},
+				model.Genre{ID: "gn-2", Name: "Rock", AlbumCount: 3, SongCount: 3},
+			))
+		})
+	})
+	Describe("Put()", Ordered, func() {
+		It("does not insert existing genre names", func() {
+			g := model.Genre{Name: "Rock"}
+			err := repo.Put(&g)
+			Expect(err).To(BeNil())
+			Expect(g.ID).To(Equal("gn-2"))
+
+			genres, _ := repo.GetAll()
+			Expect(genres).To(HaveLen(2))
+		})
+
+		It("insert non-existent genre names", func() {
+			g := model.Genre{Name: "Reggae"}
+			err := repo.Put(&g)
+			Expect(err).To(BeNil())
+
+			// ID is a uuid
+			_, err = uuid.Parse(g.ID)
+			Expect(err).To(BeNil())
+
+			genres, _ := repo.GetAll()
+			Expect(genres).To(HaveLen(3))
+			Expect(genres).To(ContainElement(model.Genre{ID: g.ID, Name: "Reggae", AlbumCount: 0, SongCount: 0}))
+		})
 	})
 })