feat(account): unlink game accounts on the shard before an account is deleted (MODULE_API 1.20.0)

ACCOUNT_DELETION.md §4.4 (AD10, AD11). api.onUserDeleting queues every linked
account in the new shard_pending_unlinks table, then calls the sidecar's
DELETE /link/{account} (actor web:account-deletion) and drops the mirror on 200/404.
A shard that is away leaves the row pending, retried on WS reconnect and on a live
server.hello; a protected account (403) is refused and listed on Admin -> Shard as
still linked on the shard. A live mob.login without the deleted user's webId clears
the row. coreApi ^1.20.0; core-ref pinned to website#232's merge (7bd93b8).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E14m6SuuY6i1vASFeGDBeY

swagger-fragment.json

@@ -1452,10 +1452,10 @@
           "Admin · Shard"
         ],
         "summary": "Get uo-link config + live status + ingestion stats (admin only)",
-        "description": "",
+        "description": "pendingUnlinks lists the game accounts a website account deletion left linked on the shard: state pending (the shard was away; retried when the bridge reconnects) or refused (a protected staff account; shard staff clear it by hand). A row goes once the shard reports a login on the account without the deleted user id.",
         "responses": {
           "200": {
-            "description": "Masked config, health and ingestion stats",
+            "description": "Masked config, health, ingestion stats and pendingUnlinks",
             "content": {
               "application/json": {
                 "schema": {