Add structured logging with zerolog

- Implement zerolog logger package with configurable levels
- Add contextual logging middleware (request_id, user_id, method, path, status, duration)
- Support both JSON (production) and human-readable (development) formats
- Add LOG_LEVEL and ENVIRONMENT configuration variables
- Replace standard log calls with structured logger throughout application
- Integrate logger in HTTP router and auth middleware

go.mod

@@ -11,9 +11,12 @@ require (
 	github.com/golang-jwt/jwt/v5 v5.3.0
 	github.com/google/uuid v1.6.0
 	github.com/joho/godotenv v1.5.1
+	github.com/rs/zerolog v1.34.0
 	github.com/swaggo/http-swagger v1.3.4
 	github.com/swaggo/swag v1.16.4
 	golang.org/x/crypto v0.45.0
+	golang.org/x/text v0.31.0
+	gopkg.in/mail.v2 v2.3.1
 	modernc.org/sqlite v1.40.1
 )
 
@@ -27,17 +30,17 @@ require (
 	github.com/go-openapi/swag v0.19.15 // indirect
 	github.com/josharian/intern v1.0.0 // indirect
 	github.com/mailru/easyjson v0.7.6 // indirect
+	github.com/mattn/go-colorable v0.1.13 // indirect
 	github.com/mattn/go-isatty v0.0.20 // indirect
 	github.com/ncruces/go-strftime v0.1.9 // indirect
+	github.com/pkg/errors v0.9.1 // indirect
 	github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec // indirect
 	github.com/swaggo/files v0.0.0-20220610200504-28940afbdbfe // indirect
 	golang.org/x/exp v0.0.0-20250620022241-b7579e27df2b // indirect
 	golang.org/x/net v0.47.0 // indirect
 	golang.org/x/sys v0.38.0 // indirect
-	golang.org/x/text v0.31.0 // indirect
 	golang.org/x/tools v0.38.0 // indirect
 	gopkg.in/alexcesaro/quotedprintable.v3 v3.0.0-20150716171945-2caba252f4dc // indirect
-	gopkg.in/mail.v2 v2.3.1 // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect
 	modernc.org/libc v1.66.10 // indirect
 	modernc.org/mathutil v1.7.1 // indirect