refactor(auth): replace untyped JWT claims with typed Claims struct

Introduced a typed Claims struct in core/auth to replace the raw
map[string]any approach used for JWT claims throughout the codebase.
This provides compile-time safety and better readability when creating,
validating, and extracting JWT tokens. Also upgraded lestrrat-go/jwx
from v2 to v3 and go-chi/jwtauth to v5.4.0, adapting all callers to
the new API where token accessor methods now return tuples instead of
bare values. Updated all affected handlers, middleware, and tests.

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

plugins/host_artwork_test.go

@@ -229,11 +229,10 @@ func decodeArtworkURL(artworkURL string) model.ArtworkID {
 	token, err := auth.TokenAuth.Decode(tokenPart)
 	Expect(err).ToNot(HaveOccurred(), "Failed to decode JWT token")
 
-	claims, err := token.AsMap(context.Background())
-	Expect(err).ToNot(HaveOccurred(), "Failed to get claims from token")
+	c := auth.ClaimsFromToken(token)
 
-	id, ok := claims["id"].(string)
-	Expect(ok).To(BeTrue(), "Token should contain 'id' claim")
+	id := c.ID
+	Expect(id).ToNot(BeEmpty(), "Token should contain 'id' claim")
 
 	artID, err := model.ParseArtworkID(id)
 	Expect(err).ToNot(HaveOccurred(), "Failed to parse artwork ID from token")