feat(web+api): 贡献表单按 archive_kind 动态生成字段

- categories 接口返回 archive_kind
- 新增公开只读接口 /api/v1/kind-fields?kind=X 返回字段模板
- 投稿 payload 支持通用 attributes,审核通过写入 product.attributes (JSONB 合并)
- food_detail 仅在含食品数据时才 upsert (药品/3C/通用不再产生空行)
- 前端 Contribute 按所选品类 archive_kind 动态渲染字段
  (食品营养 / 药品 18 字段 / 3C / 通用),除商品名外均选填

Co-Authored-By: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

api/internal/store/store.go

@@ -501,12 +501,13 @@ type Category struct {
 	Path         string  `json:"path"`
 	GPCBrickCode *string `json:"gpc_brick_code"`
 	Level        int     `json:"level"`
+	ArchiveKind  string  `json:"archive_kind"`
 }
 
 // ListCategories returns the full category tree ordered by path.
 func (s *Store) ListCategories(ctx context.Context) ([]Category, error) {
 	rows, err := s.pool.Query(ctx,
-		"SELECT id, name_zh, name_en, path::text, gpc_brick_code, level FROM category ORDER BY path")
+		"SELECT id, name_zh, name_en, path::text, gpc_brick_code, level, COALESCE(archive_kind, 'generic') FROM category ORDER BY path")
 	if err != nil {
 		return nil, err
 	}
@@ -514,7 +515,7 @@ func (s *Store) ListCategories(ctx context.Context) ([]Category, error) {
 	out := []Category{}
 	for rows.Next() {
 		var c Category
-		if err := rows.Scan(&c.ID, &c.NameZH, &c.NameEN, &c.Path, &c.GPCBrickCode, &c.Level); err != nil {
+		if err := rows.Scan(&c.ID, &c.NameZH, &c.NameEN, &c.Path, &c.GPCBrickCode, &c.Level, &c.ArchiveKind); err != nil {
 			return nil, err
 		}
 		out = append(out, c)
@@ -522,6 +523,45 @@ func (s *Store) ListCategories(ctx context.Context) ([]Category, error) {
 	return out, rows.Err()
 }
 
+// KindField describes one editable spec field for an archive kind. It drives
+// the dynamic contribution form (public, read-only view of the template).
+type KindField struct {
+	Kind        string   `json:"kind"`
+	FieldKey    string   `json:"field_key"`
+	GroupLabel  string   `json:"group_label"`
+	LabelZH     string   `json:"label_zh"`
+	FieldType   string   `json:"field_type"`
+	Unit        *string  `json:"unit"`
+	Options     []string `json:"options"`
+	Placeholder *string  `json:"placeholder"`
+	SortOrder   int      `json:"sort_order"`
+	Qualified   bool     `json:"qualified"`
+}
+
+// ListKindFields returns the ordered field template for one archive kind so the
+// public contribution form can render kind-specific inputs.
+func (s *Store) ListKindFields(ctx context.Context, kind string) ([]KindField, error) {
+	rows, err := s.pool.Query(ctx, `
+SELECT kind, field_key, group_label, label_zh, field_type, unit, options,
+       placeholder, sort_order, qualified
+FROM kind_field WHERE kind = $1 ORDER BY sort_order, field_key`, kind)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	out := []KindField{}
+	for rows.Next() {
+		var f KindField
+		if err := rows.Scan(&f.Kind, &f.FieldKey, &f.GroupLabel, &f.LabelZH,
+			&f.FieldType, &f.Unit, &f.Options, &f.Placeholder, &f.SortOrder,
+			&f.Qualified); err != nil {
+			return nil, err
+		}
+		out = append(out, f)
+	}
+	return out, rows.Err()
+}
+
 // APIKey is the minimal metadata the public API needs to authorize a caller.
 type APIKey struct {
 	ID              string