Add Status field to Item model

Items now have a status field ('pass' or 'fail') to control whether they
can be published. Items marked 'fail' will be skipped during publishing
and have their existing posts deleted.

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

models.go

@@ -99,6 +99,9 @@ type Item struct {
 	ImageURLs []string   `json:"image_urls,omitempty"` // Image URLs extracted from content
 	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"`