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>

core/auth/claims_test.go

@@ -0,0 +1,99 @@
+package auth_test
+
+import (
+	"time"
+
+	"github.com/go-chi/jwtauth/v5"
+	"github.com/navidrome/navidrome/core/auth"
+	. "github.com/onsi/ginkgo/v2"
+	. "github.com/onsi/gomega"
+)
+
+var _ = Describe("Claims", func() {
+	Describe("ToMap", func() {
+		It("includes only non-zero fields", func() {
+			c := auth.Claims{
+				Issuer:  "ND",
+				Subject: "johndoe",
+				UserID:  "123",
+				IsAdmin: true,
+			}
+			m := c.ToMap()
+			Expect(m).To(HaveKeyWithValue("iss", "ND"))
+			Expect(m).To(HaveKeyWithValue("sub", "johndoe"))
+			Expect(m).To(HaveKeyWithValue("uid", "123"))
+			Expect(m).To(HaveKeyWithValue("adm", true))
+			Expect(m).NotTo(HaveKey("exp"))
+			Expect(m).NotTo(HaveKey("iat"))
+			Expect(m).NotTo(HaveKey("id"))
+			Expect(m).NotTo(HaveKey("f"))
+			Expect(m).NotTo(HaveKey("b"))
+		})
+
+		It("includes expiration and issued-at when set", func() {
+			now := time.Now()
+			c := auth.Claims{
+				IssuedAt:  now,
+				ExpiresAt: now.Add(time.Hour),
+			}
+			m := c.ToMap()
+			Expect(m).To(HaveKey("iat"))
+			Expect(m).To(HaveKey("exp"))
+		})
+
+		It("includes custom claims for public tokens", func() {
+			c := auth.Claims{
+				ID:      "al-123",
+				Format:  "mp3",
+				BitRate: 192,
+			}
+			m := c.ToMap()
+			Expect(m).To(HaveKeyWithValue("id", "al-123"))
+			Expect(m).To(HaveKeyWithValue("f", "mp3"))
+			Expect(m).To(HaveKeyWithValue("b", 192))
+		})
+	})
+
+	Describe("ClaimsFromToken", func() {
+		It("round-trips session claims through encode/decode", func() {
+			tokenAuth := jwtauth.New("HS256", []byte("test-secret"), nil)
+			now := time.Now().Truncate(time.Second)
+			original := auth.Claims{
+				Issuer:  "ND",
+				Subject: "johndoe",
+				UserID:  "123",
+				IsAdmin: true,
+			}
+			m := original.ToMap()
+			m["iat"] = now.UTC().Unix()
+			token, _, err := tokenAuth.Encode(m)
+			Expect(err).NotTo(HaveOccurred())
+
+			c := auth.ClaimsFromToken(token)
+			Expect(c.Issuer).To(Equal("ND"))
+			Expect(c.Subject).To(Equal("johndoe"))
+			Expect(c.UserID).To(Equal("123"))
+			Expect(c.IsAdmin).To(BeTrue())
+			Expect(c.IssuedAt.UTC()).To(Equal(now.UTC()))
+		})
+
+		It("round-trips public token claims through encode/decode", func() {
+			tokenAuth := jwtauth.New("HS256", []byte("test-secret"), nil)
+			original := auth.Claims{
+				Issuer:  "ND",
+				ID:      "al-456",
+				Format:  "opus",
+				BitRate: 128,
+			}
+			token, _, err := tokenAuth.Encode(original.ToMap())
+			Expect(err).NotTo(HaveOccurred())
+
+			c := auth.ClaimsFromToken(token)
+			Expect(c.Issuer).To(Equal("ND"))
+			Expect(c.ID).To(Equal("al-456"))
+			Expect(c.Format).To(Equal("opus"))
+			Expect(c.BitRate).To(Equal(128))
+		})
+	})
+
+})