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/client.ts

@@ -6,6 +6,7 @@
 
 import type {
   AccountRef,
+  BlockList,
   BlockStatus,
   ChatMessage,
   EvalResult,
@@ -127,8 +128,8 @@ export interface GatewayClient {
   friendCodeRedeem(code: string): Promise<AccountRef>;
 
   // --- blocks ---
-  blocksList(): Promise<AccountRef[]>;
-  block(accountId: string): Promise<void>;
+  blocksList(): Promise<BlockList>;
+  block(accountId: string, gameId?: string): Promise<void>;
   unblock(accountId: string): Promise<void>;
 
   // --- invitations ---