chore(deps): upgrade core dependencies

- pgx/v5: v5.4.3 → v5.8.0
- golang-jwt/jwt/v5: v5.3.0 → v5.3.1
- echo/v4: v4.13.4 → v4.15.1
- google/uuid: v1.4.0 → v1.6.0
- golang.org/x/crypto: v0.46.0 → v0.48.0
- golang.org/x/text: v0.33.0 → v0.34.0

Also updates indirect dependencies including puddle/v2, brotli,
regexp2, and other transitive deps.

Build and tests passing with pgx v5.8.0 (internal/anynil package
removed but not used by our code).

internal/handlers/auth.go

@@ -10,7 +10,7 @@ import (
 	"strings"
 	"time"
 
-	jwt "github.com/golang-jwt/jwt/v5"
+	"github.com/golang-jwt/jwt/v5"
 
 	"github.com/google/uuid"
 	"github.com/jackc/pgx/v5"