Retention follows per-user read and starred

reap_candidates still read entries.read/flagged, which nothing writes
since read state moved to entry_state -- so starring no longer protected
a file and the read-first ordering was dead. One file serves every
subscriber, so anyone starring it keeps it, and it counts as read only
once everyone subscribed has read it.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AdXho5tTkjFLeUXKbEjKBh

src/retention.rs

@@ -150,22 +150,39 @@ mod tests {
     }
 
     #[test]
-    fn query_never_offers_flagged_files_and_prefers_read_ones() {
+    fn query_never_offers_a_file_anyone_starred_and_prefers_ones_everyone_read() {
+        // One file serves both subscribers, so it takes both of them to release it.
         let db = Db::memory().unwrap();
         db.exec_for_test(
-            "INSERT INTO entries (feed_id, guid, first_seen, read, flagged) VALUES
-                ('f', 'keep',   0, 1, 1),
-                ('f', 'unread', 0, 0, 0),
-                ('f', 'read',   0, 1, 0);
+            "INSERT INTO users (id, name, is_admin, created) VALUES (1,'ray',1,0),(2,'sam',0,0);
+             INSERT INTO subscriptions (user_id, feed_id, created) VALUES (1,'f',0),(2,'f',0);
+             INSERT INTO entries (feed_id, guid, first_seen) VALUES
+                ('f', 'keep',   0),
+                ('f', 'half',   0),
+                ('f', 'unread', 0),
+                ('f', 'read',   0);
+             -- Starred by one of the two, so it stays whatever the other thinks.
+             INSERT INTO entry_state (user_id, feed_id, guid, read, flagged) VALUES
+                (1, 'f', 'keep',   1, 1),
+                (2, 'f', 'keep',   1, 0),
+                (1, 'f', 'half',   1, 0),
+                (1, 'f', 'read',   1, 0),
+                (2, 'f', 'read',   1, 0);
              INSERT INTO enclosures (id, feed_id, guid, url, path, bytes_done, state, downloaded_at) VALUES
                 (1, 'f', 'keep',   'u1', '/tmp/keep',   10, 'done', 10),
-                (2, 'f', 'unread', 'u2', '/tmp/unread', 10, 'done', 20),
-                (3, 'f', 'read',   'u3', '/tmp/read',   10, 'done', 30);",
+                (2, 'f', 'half',   'u2', '/tmp/half',   10, 'done', 20),
+                (3, 'f', 'unread', 'u3', '/tmp/unread', 10, 'done', 30),
+                (4, 'f', 'read',   'u4', '/tmp/read',   10, 'done', 40);",
         )
         .unwrap();
 
         let got: Vec<i64> = db.reap_candidates().unwrap().iter().map(|c| c.id).collect();
-        assert_eq!(got, vec![3, 2], "flagged excluded; read goes before unread");
+        assert_eq!(
+            got,
+            vec![4, 2, 3],
+            "starred by anyone is never offered; read by everyone goes first, and one \
+             person still having it unread keeps it back with the unread ones"
+        );
     }
 
     #[test]