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/gen/fbs/scrabblefb.ts

@@ -59,6 +59,7 @@ export { PlayTile } from './scrabblefb/play-tile.js';
 export { Profile } from './scrabblefb/profile.js';
 export { RedeemCodeRequest } from './scrabblefb/redeem-code-request.js';
 export { RedeemResult } from './scrabblefb/redeem-result.js';
+export { RobotBlockRef } from './scrabblefb/robot-block-ref.js';
 export { SeatView } from './scrabblefb/seat-view.js';
 export { Session } from './scrabblefb/session.js';
 export { StateRequest } from './scrabblefb/state-request.js';