Phase 19: persistent notifications system

New notifications table (migration 0009) stores event-driven alerts
alongside the existing dynamic state notifications (unclaimed objectives,
expiring loans, season ending soon).

Persistent notifications are created automatically during match
processing: one per level gained, one per expired loan card, one per
objective newly completed, and one when a season ends (with
promotion/relegation result and rewards in the body).

GET /notifications now returns a merged list — persistent entries
(newest-first, limit 50) followed by dynamic entries — plus an
unread_count for the badge. Each item carries type, title, body,
is_read, and (for persistent) id and created_at.

PATCH /notifications/:id/read marks a single persistent notification
read. POST /notifications/read-all marks all persistent ones read.

Four new tests: unread_count field, level-up notification creation,
mark-all-read, single-read PATCH. Core now at 77 tests.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/app.rs

@@ -18,7 +18,7 @@ use anyhow::Result;
 use axum::{
     extract::DefaultBodyLimit,
     middleware,
-    routing::{delete, get, post, put},
+    routing::{delete, get, patch, post, put},
     Router,
 };
 use std::sync::Arc;
@@ -195,6 +195,8 @@ pub async fn build(pool: Pool, cfg: Config) -> Result<Router> {
         .route("/settings", put(routes::settings::put_settings))
         .route("/division", get(routes::division::get_division))
         .route("/notifications", get(routes::notifications::get_notifications))
+        .route("/notifications/read-all", post(routes::notifications::mark_all_notifications_read))
+        .route("/notifications/:id/read", patch(routes::notifications::mark_notification_read))
         .route("/fut-champs", get(routes::fut_champs::get_fut_champs))
         .route("/fut-champs/start", post(routes::fut_champs::post_start_fut_champs))
         .route("/fut-champs/history", get(routes::fut_champs::get_champs_history))