Add unqueue (delete) button to web reading view

Adds a delete route and handler to the web UI so documents can be
removed directly from the reading page. Uses CSRF-protected POST with a
browser confirmation dialog. Styled with a danger accent.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

internal/webserver/server.go

@@ -70,6 +70,7 @@ func (s *Server) RegisterRoutes(r chi.Router) {
 		r.Get("/d/{slug}", s.handleRead)
 		r.Post("/d/{slug}/read", s.handleMarkRead)
 		r.Post("/d/{slug}/unread", s.handleMarkUnread)
+		r.Post("/d/{slug}/delete", s.handleDelete)
 		r.Post("/logout", s.handleLogout)
 	})
 }
@@ -176,3 +177,11 @@ func (s *Server) handleMarkUnread(w http.ResponseWriter, r *http.Request) {
 	}
 	http.Redirect(w, r, "/", http.StatusFound)
 }
+
+func (s *Server) handleDelete(w http.ResponseWriter, r *http.Request) {
+	slug := chi.URLParam(r, "slug")
+	if err := s.db.DeleteDocument(slug); err != nil {
+		s.logger.Error("failed to delete document", "slug", slug, "error", err)
+	}
+	http.Redirect(w, r, "/", http.StatusFound)
+}