dudu MVP：五端语音输入法初始提交

- server：Go 网关（WS 流式识别中继/计费配额/微信登录支付 mock/反馈/埋点），gummy provider 已真实联调
- desktop：Tauri 2（全局快捷键 push-to-talk/浮层/托盘/设置/登录购买/反馈/首启引导）
- android：Compose 主 App + IME（键盘内录音直传）
- ios：App + 键盘扩展（1A spike 实证键盘内不可录音，走 deep link 听写）
- design/design-pipeline：设计系统 + token 导出 iOS/Android 主题
- doc：前后端设计文档（HTML）；web：官网宣传页；todo：任务看板

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

server/internal/feedback/feedback.go

@@ -0,0 +1,146 @@
+// Package feedback 用户反馈：文字 + 图片（≤3 张，magic bytes 校验）+ 诊断信息。
+// Storage 抽象对象存储：生产为阿里云 OSS，开发期 LocalStorage 落本地盘。
+// 设计见 doc/backend-architecture.html 3.5。
+package feedback
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"github.com/gin-gonic/gin"
+	"github.com/google/uuid"
+	"github.com/redis/go-redis/v9"
+	"gorm.io/datatypes"
+	"gorm.io/gorm"
+
+	"dudu/server/internal/auth"
+	"dudu/server/internal/store"
+	"dudu/server/pkg/protocol"
+)
+
+type Storage interface {
+	Save(ctx context.Context, key string, data []byte, contentType string) error
+}
+
+// LocalStorage 开发期实现：写入本地目录（生产替换为 OSS 实现）。
+type LocalStorage struct{ Dir string }
+
+func (s LocalStorage) Save(_ context.Context, key string, data []byte, _ string) error {
+	path := filepath.Join(s.Dir, key)
+	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
+		return err
+	}
+	return os.WriteFile(path, data, 0o644)
+}
+
+// sniffImage magic bytes 验真实格式（伪造扩展名拒绝）。
+func sniffImage(data []byte) (ext, contentType string, ok bool) {
+	switch {
+	case bytes.HasPrefix(data, []byte{0xFF, 0xD8, 0xFF}):
+		return "jpg", "image/jpeg", true
+	case bytes.HasPrefix(data, []byte{0x89, 'P', 'N', 'G'}):
+		return "png", "image/png", true
+	case len(data) > 12 && bytes.Equal(data[0:4], []byte("RIFF")) && bytes.Equal(data[8:12], []byte("WEBP")):
+		return "webp", "image/webp", true
+	}
+	return "", "", false
+}
+
+type Handlers struct {
+	DB      *gorm.DB
+	RDB     *redis.Client
+	Storage Storage
+}
+
+// Submit POST /v1/feedback（multipart，需登录）。
+func (h *Handlers) Submit(c *gin.Context) {
+	uid := auth.UserID(c)
+
+	// 限频：每用户 10 条/天
+	day := store.Day(time.Now())
+	n, err := store.IncrDailyCounter(c, h.RDB, store.KeyRateFb(uid, day))
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, protocol.NewAPIError(protocol.ErrInternal))
+		return
+	}
+	if n > protocol.FeedbackDailyLimit {
+		c.JSON(http.StatusTooManyRequests, protocol.NewAPIError(protocol.ErrFeedbackRateLimited))
+		return
+	}
+
+	content := strings.TrimSpace(c.PostForm("content"))
+	if l := len([]rune(content)); l == 0 || l > protocol.FeedbackMaxContentLen {
+		c.JSON(http.StatusBadRequest, protocol.NewAPIError(protocol.ErrBadRequest))
+		return
+	}
+
+	form, err := c.MultipartForm()
+	if err != nil {
+		c.JSON(http.StatusBadRequest, protocol.NewAPIError(protocol.ErrBadRequest))
+		return
+	}
+	files := form.File["images[]"]
+	if len(files) == 0 {
+		files = form.File["images"]
+	}
+	if len(files) > protocol.FeedbackMaxImages {
+		c.JSON(http.StatusBadRequest, protocol.NewAPIError(protocol.ErrBadRequest))
+		return
+	}
+
+	id := "fb" + strings.ReplaceAll(uuid.NewString(), "-", "")[:22]
+	var keys []string
+	for i, fh := range files {
+		if fh.Size > protocol.FeedbackMaxImageBytes {
+			c.JSON(http.StatusBadRequest, protocol.NewAPIError(protocol.ErrBadRequest))
+			return
+		}
+		f, err := fh.Open()
+		if err != nil {
+			c.JSON(http.StatusBadRequest, protocol.NewAPIError(protocol.ErrBadRequest))
+			return
+		}
+		data, err := io.ReadAll(io.LimitReader(f, protocol.FeedbackMaxImageBytes+1))
+		f.Close()
+		if err != nil || len(data) > protocol.FeedbackMaxImageBytes {
+			c.JSON(http.StatusBadRequest, protocol.NewAPIError(protocol.ErrBadRequest))
+			return
+		}
+		ext, ct, ok := sniffImage(data)
+		if !ok {
+			c.JSON(http.StatusBadRequest, protocol.NewAPIError(protocol.ErrBadRequest))
+			return
+		}
+		key := fmt.Sprintf("fb/%s/%d.%s", id, i+1, ext)
+		if err := h.Storage.Save(c, key, data, ct); err != nil {
+			c.JSON(http.StatusInternalServerError, protocol.NewAPIError(protocol.ErrInternal))
+			return
+		}
+		keys = append(keys, key)
+	}
+
+	imagesJSON, _ := json.Marshal(keys)
+	var diagJSON datatypes.JSON
+	if d := c.PostForm("diagnostics"); d != "" && len(d) < 64<<10 && json.Valid([]byte(d)) {
+		diagJSON = datatypes.JSON(d)
+	}
+	fb := store.Feedback{
+		ID: id, UserID: uid, Content: content,
+		Images: datatypes.JSON(imagesJSON), Diagnostics: diagJSON,
+		Platform: c.GetHeader("X-Platform"), AppVersion: c.GetHeader("X-App-Version"),
+		Status: store.FeedbackNew,
+	}
+	if err := h.DB.Create(&fb).Error; err != nil {
+		c.JSON(http.StatusInternalServerError, protocol.NewAPIError(protocol.ErrInternal))
+		return
+	}
+	c.JSON(http.StatusOK, protocol.FeedbackResponse{FeedbackID: id})
+}