feat(deezer): Add artist bio, top tracks, related artists and language support (#4720)

* feat(deezer): add functions to fetch related artists, biographies, and top tracks for an artist

Signed-off-by: Deluan <deluan@navidrome.org>

* feat(deezer): add language support for Deezer API client

Signed-off-by: Deluan <deluan@navidrome.org>

* fix(deezer): Use GraphQL API for translated biographies

The previous implementation scraped the __DZR_APP_STATE__ from HTML,
which only contained English content. The actual biography displayed
on Deezer's website comes from their GraphQL API at pipe.deezer.com,
which properly respects the Accept-Language header and returns
translated content.

This change:
- Switches from HTML scraping to the GraphQL API
- Uses Accept-Language header instead of URL path for language
- Updates tests to match the new implementation
- Removes unused HTML fixture file

Signed-off-by: Deluan <deluan@navidrome.org>

* refactor(deezer): move JWT token handling to a separate file for better organization

Signed-off-by: Deluan <deluan@navidrome.org>

* feat(deezer): enhance JWT token handling with expiration validation

Signed-off-by: Deluan <deluan@navidrome.org>

* refactor(deezer): change log level for unknown agent warnings from Warn to Debug

Signed-off-by: Deluan <deluan@navidrome.org>

* fix(deezer): reduce JWT token expiration buffer from 10 minutes to 1 minute

Signed-off-by: Deluan <deluan@navidrome.org>

---------

Signed-off-by: Deluan <deluan@navidrome.org>

core/agents/deezer/responses_test.go

@@ -35,4 +35,35 @@ var _ = Describe("Responses", func() {
 			Expect(errorResp.Error.Message).To(Equal("Missing parameters: q"))
 		})
 	})
+
+	Describe("Related Artists", func() {
+		It("parses the related artists response correctly", func() {
+			var resp RelatedArtists
+			body, err := os.ReadFile("tests/fixtures/deezer.artist.related.json")
+			Expect(err).To(BeNil())
+			err = json.Unmarshal(body, &resp)
+			Expect(err).To(BeNil())
+
+			Expect(resp.Data).To(HaveLen(20))
+			justice := resp.Data[0]
+			Expect(justice.Name).To(Equal("Justice"))
+			Expect(justice.ID).To(Equal(6404))
+		})
+	})
+
+	Describe("Top Tracks", func() {
+		It("parses the top tracks response correctly", func() {
+			var resp TopTracks
+			body, err := os.ReadFile("tests/fixtures/deezer.artist.top.json")
+			Expect(err).To(BeNil())
+			err = json.Unmarshal(body, &resp)
+			Expect(err).To(BeNil())
+
+			Expect(resp.Data).To(HaveLen(5))
+			track := resp.Data[0]
+			Expect(track.Title).To(Equal("Instant Crush (feat. Julian Casablancas)"))
+			Expect(track.ID).To(Equal(67238732))
+			Expect(track.Album.Title).To(Equal("Random Access Memories"))
+		})
+	})
 })