Block lists: words that hide items and keep them from downloading (#47)

Each person has a list for every feed they read and one per feed. An item whose title or text
holds one of the words, matched as whole words so "ai" does not hide everything that "said"
anything, is hidden from them and, since the scanner now keeps each subscriber's filters
separate, is fetched only if someone else still wants it.

Whole-word matching is not something LIKE can do on both SQLite and Postgres, so the matches are
worked out in Rust into a `hidden` table whenever a list changes, someone subscribes, or a scan
brings in new items, and the queries only look that table up. Both new tables are tables rather
than columns because create_missing adds tables but never columns. Hidden counts as read for
the reaper and for "others still want this file", since whoever it is hidden from is as done
with it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/entity.rs

@@ -228,6 +228,46 @@ pub mod entry_state {
     owned_by_user!();
 }
 
+/// Words someone never wants to see: an item whose title or text has one is hidden from them and
+/// not downloaded on their account (issue #47). `feed_id` is empty for the list that applies to
+/// every feed they read.
+pub mod blocklists {
+    use sea_orm::entity::prelude::*;
+
+    #[derive(Clone, Debug, PartialEq, Eq, DeriveEntityModel)]
+    #[sea_orm(table_name = "blocklists")]
+    pub struct Model {
+        #[sea_orm(primary_key, auto_increment = false)]
+        pub user_id: i64,
+        #[sea_orm(primary_key, auto_increment = false, column_type = "Text")]
+        pub feed_id: String,
+        /// JSON array of strings.
+        #[sea_orm(column_type = "Text")]
+        pub words: String,
+    }
+
+    owned_by_user!();
+}
+
+/// The items someone's block lists hide from them, worked out whenever a list or the feed
+/// changes (`Db::rehide`), since SQL on both databases cannot match whole words itself.
+pub mod hidden {
+    use sea_orm::entity::prelude::*;
+
+    #[derive(Clone, Debug, PartialEq, Eq, DeriveEntityModel)]
+    #[sea_orm(table_name = "hidden")]
+    pub struct Model {
+        #[sea_orm(primary_key, auto_increment = false)]
+        pub user_id: i64,
+        #[sea_orm(primary_key, auto_increment = false, column_type = "Text")]
+        pub feed_id: String,
+        #[sea_orm(primary_key, auto_increment = false, column_type = "Text")]
+        pub guid: String,
+    }
+
+    owned_by_user!();
+}
+
 pub mod sessions {
     use sea_orm::entity::prelude::*;