fix(sync): short sync transactions, real Steam retries, no N+1

src/main/resources/application.yml

@@ -87,6 +87,13 @@ resilience4j:
         retry-exceptions:
           - org.springframework.web.client.RestClientException
           - org.springframework.web.client.ResourceAccessException
+        # A 4xx (a refused key, a private list) is the same on the next try.
+        ignore-exceptions:
+          - org.springframework.web.client.HttpClientErrorException
+      # Calls a page waits for, and the optional wishlist: one try, else a Steam outage holds every page (or the
+      # sync) for three read timeouts.
+      steamApiOnce:
+        max-attempts: 1
   ratelimiter:
     instances:
       steamApi:

src/main/resources/db/migration/V23__Sync_Started_At.sql

@@ -0,0 +1,3 @@
+-- The claim of a sync is committed on its own now; a RUNNING row is stale by the start of its run, not by the end of
+-- the last one.
+ALTER TABLE user_steam_sync ADD COLUMN sync_started_at TIMESTAMPTZ;