Remove publishing fields from Item struct

- Removed Status, PublishedAt, PublishedUri fields
- Items table is now a pure work queue
- PDS is source of truth for published content

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

models.go

@@ -53,12 +53,6 @@ type Item struct {
 	ImageURLs []string   `json:"image_urls,omitempty"` // Image URLs extracted from description
 	Tags      []string   `json:"tags,omitempty"`       // Category/tag strings from feed
 
-	// Item status: "pass" (default, can publish), "fail" (rejected, delete if published)
-	Status string `json:"status,omitempty"`
-
-	// Publishing to PDS
-	PublishedAt  time.Time `json:"published_at,omitempty"`
-	PublishedUri string    `json:"published_uri,omitempty"`
 }
 
 // ShortURL represents a shortened URL mapping