fix(social): robot blocks

Blocking an auto-match opponent who is secretly a pooled robot is recorded  instead in a separate `robot_blocks` table.

Now blocking behaves the same in that game (struck name, hidden composer) and lists the blocked opponent under the name you saw, but is recorded only against that game — the disguise holds, the shared robot is never globally blocked, and the matchmaker keeps pairing you with robots (so you can never block yourself out of opponents).

- the shared robot account is never put in `blocks`
- the matchmaker keeps it free and it is not blocked under its other per-game names
- the blocked list and the in-game card still show it by joining that table; an unblock deletes the row

ui/src/lib/transport.ts

@@ -187,8 +187,8 @@ export function createTransport(baseUrl: string): GatewayClient {
     async blocksList() {
       return codec.decodeBlockList(await exec('blocks.list', codec.empty()));
     },
-    async block(accountId) {
-      await exec('blocks.add', codec.encodeTarget(accountId));
+    async block(accountId, gameId) {
+      await exec('blocks.add', codec.encodeTarget(accountId, gameId));
     },
     async unblock(accountId) {
       await exec('blocks.remove', codec.encodeTarget(accountId));