feat(story-2.1): add feed model and add-feed-by-url API

internal/domain/feed.go

@@ -0,0 +1,37 @@
+package domain
+
+import (
+	"time"
+
+	"github.com/google/uuid"
+)
+
+// Feed represents an RSS/Atom feed subscription.
+type Feed struct {
+	ID            uuid.UUID  `json:"id"`
+	UserID        uuid.UUID  `json:"user_id"`
+	URL           string     `json:"url"`
+	Title         string     `json:"title"`
+	Description   string     `json:"description,omitempty"`
+	SiteURL       string     `json:"site_url,omitempty"`
+	ImageURL      string     `json:"image_url,omitempty"`
+	LastFetchedAt *time.Time `json:"last_fetched_at,omitempty"`
+	FetchError    string     `json:"fetch_error,omitempty"`
+	CreatedAt     time.Time  `json:"created_at"`
+	UpdatedAt     time.Time  `json:"updated_at"`
+
+	// Virtual fields (not in DB)
+	UnreadCount int `json:"unread_count,omitempty"`
+}
+
+// FeedRepository defines the interface for feed data access.
+type FeedRepository interface {
+	Create(feed *Feed) error
+	GetByID(id uuid.UUID) (*Feed, error)
+	GetByUserID(userID uuid.UUID) ([]*Feed, error)
+	GetByURL(userID uuid.UUID, url string) (*Feed, error)
+	Update(feed *Feed) error
+	Delete(id uuid.UUID) error
+	GetFeedsToFetch(limit int) ([]*Feed, error)
+	UpdateFetchStatus(id uuid.UUID, fetchedAt time.Time, fetchError string) error
+}