feat(store): persist points.board and serve it from GET /points

Protocol 3.0 §7 (docs/link/v3.md). The shard publishes ~25 points/loyalty
leaderboards as one points.board frame per system; the sidecar folds each into a
projection table and serves them back, so the site's leaderboards page renders
during a shard outage.

  - points_boards(system PK, name, json, updated_t), keyed by the shard's own
    PointsType name. `name` is hoisted only for the ORDER BY.
  - main.rs gains a points.board arm keyed on `system`, alongside the existing
    champ/guild/governor/house/ruleset projections. There is deliberately no
    delete counterpart: the shard's set of point systems is fixed at startup, so
    it emits no points.remove — the same shape the governor board already has.
  - GET /points returns every board ordered by display name; GET /points/:system
    returns one, or 404 when the shard has never published that system. 404 and
    "a published board nobody has scored in yet" (200, empty top) are different
    answers, and the website renders them differently.

Store-backed rather than an RPC for the same reason as the other boards, and it
matters more here: these are standings accumulated over months, so blanking them
during a shard restart reads as data loss rather than as staleness.

PROTOCOL_VERSION stays at 2 — the bump to 3 is the one-time edge → main cutover
in v3.md §4, not a per-phase change.

cargo build and cargo clippy --all-targets are clean. Smoke-tested against a
driver on the loopback link: two boards stored and served, a re-emitted system
overwriting rather than accumulating, 404 for an unknown system, 401
unauthenticated. Also verified against the real ServUO shard, which fed five
live boards through this path.

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

sidecar/src/store.rs

@@ -322,6 +322,55 @@ impl Store {
         Ok(row.and_then(|r| serde_json::from_str(&r.get::<String, _>("json")).ok()))
     }
 
+    // ---- points / loyalty boards (Protocol 3.0) ----
+
+    /// Upserts one system's leaderboard, keyed by its `PointsType` name (`QueensLoyalty`,
+    /// `CleanUpBritannia`, …). Fed from `points.board`; one row per system, always the most recent
+    /// top-N snapshot.
+    ///
+    /// There is no matching delete, and that is deliberate rather than an omission: the shard's set
+    /// of point systems is fixed at startup by `PointsSystem.Configure`, so a system cannot vanish
+    /// at runtime and the plugin emits no `points.remove`. Same argument the governor board makes.
+    pub async fn upsert_points_board(
+        &self,
+        system: &str,
+        name: Option<&str>,
+        json: &str,
+        t: i64,
+    ) -> anyhow::Result<()> {
+        sqlx::query(
+            "INSERT INTO points_boards (system, name, json, updated_t) VALUES (?, ?, ?, ?)
+             ON CONFLICT(system) DO UPDATE SET name = excluded.name, json = excluded.json, updated_t = excluded.updated_t",
+        )
+        .bind(system)
+        .bind(name)
+        .bind(json)
+        .bind(t)
+        .execute(&self.pool)
+        .await?;
+        Ok(())
+    }
+
+    /// Every system's latest board, ordered by display name then system key. Systems the shard has
+    /// never published are simply absent — the website renders the set it is given.
+    pub async fn points_boards_all(&self) -> anyhow::Result<Vec<Value>> {
+        let rows = sqlx::query("SELECT json FROM points_boards ORDER BY name, system")
+            .fetch_all(&self.pool)
+            .await?;
+        Ok(parse_json_column(rows))
+    }
+
+    /// One system's board, or `None` when that system has never published one. `None` is a real
+    /// answer (an unknown system name, or one the operator excluded via `Bridge.cfg PointsSystems`),
+    /// which the website turns into a 404 rather than an empty board.
+    pub async fn points_board(&self, system: &str) -> anyhow::Result<Option<Value>> {
+        let row = sqlx::query("SELECT json FROM points_boards WHERE system = ?")
+            .bind(system)
+            .fetch_optional(&self.pool)
+            .await?;
+        Ok(row.and_then(|r| serde_json::from_str(&r.get::<String, _>("json")).ok()))
+    }
+
     // ---- Town Cryer news (Protocol 2.1) ----
 
     /// Stores/replaces one external news article (the `news.add` command json), keyed by id. The
@@ -422,6 +471,15 @@ CREATE TABLE IF NOT EXISTS news (
     updated_t INTEGER NOT NULL
 );
 
+-- Points/loyalty leaderboards (Protocol 3.0). One row per point system, keyed by the shard's
+-- own PointsType name; `name` is the resolved display name, hoisted only for the ORDER BY.
+CREATE TABLE IF NOT EXISTS points_boards (
+    system    TEXT PRIMARY KEY,
+    name      TEXT,
+    json      TEXT NOT NULL,
+    updated_t INTEGER NOT NULL
+);
+
 -- The shard's published ruleset (Protocol 3.0). Singleton: the CHECK is what makes it one,
 -- so an upsert can target id = 1 unconditionally and no second row can ever appear.
 CREATE TABLE IF NOT EXISTS ruleset (