feat: 系统优化 - ESLint、Tailwind、前端健壮性、后端工程化、运维可观测性

- 前端: ESLint+Prettier配置、Tailwind v4配置、ErrorBoundary、全局AuthLoader优化、ReactQuery分层
- 后端: MinIO凭证移除、Docker统一为govai品牌、zerolog日志封装、错误码枚举、文件上传校验、单元测试(13项全通过)
- 运维: 健康检查增强(PG/Redis ping)、Prometheus指标(/metrics端点)、多租户tenant包、RateLimit nil防御
- 移动: citation_prompt.txt → internal/assets/

server/internal/logger/logger.go

@@ -0,0 +1,62 @@
+package logger
+
+import (
+	"io"
+	"os"
+	"time"
+
+	"github.com/rs/zerolog"
+)
+
+var log zerolog.Logger
+
+func Init(level string, jsonFormat bool) {
+	var output io.Writer = os.Stdout
+	if !jsonFormat {
+		output = zerolog.ConsoleWriter{
+			Out:        os.Stdout,
+			TimeFormat: time.RFC3339,
+		}
+	}
+
+	lvl, err := zerolog.ParseLevel(level)
+	if err != nil {
+		lvl = zerolog.InfoLevel
+	}
+
+	log = zerolog.New(output).
+		Level(lvl).
+		With().
+		Timestamp().
+		Caller().
+		Logger()
+}
+
+func Get() *zerolog.Logger {
+	return &log
+}
+
+// Info/fatal/warn/error 等直接透传
+func Info() *zerolog.Event {
+	return log.Info()
+}
+
+func Warn() *zerolog.Event {
+	return log.Warn()
+}
+
+func Error() *zerolog.Event {
+	return log.Error()
+}
+
+func Debug() *zerolog.Event {
+	return log.Debug()
+}
+
+func Fatal() *zerolog.Event {
+	return log.Fatal()
+}
+
+func Ctx(ctx interface{ Value(key interface{}) interface{} }) zerolog.Logger {
+	return log.With().Interface("ctx", ctx).Logger()
+}