Pin a feed to the top of the feed list

subscriptions.pinned, per person, set by PATCH /api/feeds/{id} {pinned} and
returned as FeedRow.pinned. Kept out of Sub, which the scanner merges into its
policy; set_subscription names its columns, so saving a feed's settings leaves
the pin alone (tested).

Pinned feeds come first in the list, a pin before the name and a rule under the
block: a pinned folder with its feeds under it, a feed from inside one lifted out
of it. The pin button is on both the feed and the folder page.

Closes #33.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/web.rs

@@ -614,6 +614,8 @@ struct FeedRow {
     unread: i64,
     /// Including you. More than one means every file here is shared.
     subscribers: i64,
+    /// Pinned to the top of your list.
+    pinned: bool,
 }
 
 #[derive(Serialize)]
@@ -641,6 +643,7 @@ async fn feeds(
         .map(|s| (s.feed_id.clone(), s))
         .collect();
     let counts = state.ctx.db.subscriber_counts()?;
+    let pinned = state.ctx.db.pinned_feeds(user.id)?;
     let mut out = Vec::with_capacity(mine.len());
     for sub in &subs {
         let (id, feed) = (&sub.id, &sub.cfg);
@@ -701,6 +704,7 @@ async fn feeds(
             downloaded: s.downloaded,
             unread: state.ctx.db.unread_count(user.id, id)?,
             subscribers: counts.get(id).copied().unwrap_or(0),
+            pinned: pinned.contains(id),
         });
     }
     Ok(Json(out))
@@ -884,6 +888,13 @@ impl ApiError {
             status: StatusCode::FORBIDDEN,
         }
     }
+
+    fn not_found(msg: impl Into<String>) -> Self {
+        Self {
+            error: anyhow::Error::msg(msg.into()),
+            status: StatusCode::NOT_FOUND,
+        }
+    }
 }
 
 impl IntoResponse for ApiError {
@@ -1218,6 +1229,7 @@ struct FeedPatch {
     auto_download: Option<bool>,
     #[serde(default, deserialize_with = "double_option")]
     max_new_per_check: Option<Option<usize>>,
+    pinned: Option<bool>,
 }
 
 fn double_option<'de, T, D>(de: D) -> Result<Option<Option<T>>, D::Error>
@@ -1234,6 +1246,12 @@ async fn patch_feed(
     user: crate::db::User,
     Json(body): Json<FeedPatch>,
 ) -> Result<StatusCode, ApiError> {
+    // Pinning is yours alone too, and means nothing for a feed you do not subscribe to.
+    if let Some(on) = body.pinned
+        && !state.ctx.db.set_pinned(user.id, &id, on)?
+    {
+        return Err(ApiError::not_found("you do not subscribe to that feed"));
+    }
     // What one person wants -- which items, whether to fetch them, how many at a time --
     // is theirs. It goes on their subscription and nobody else sees the change.
     if state.ctx.db.subscription(user.id, &id)?.is_some() {