chore(jet): regenerate the backend jet to match the migrations

The committed go-jet code had drifted from the schema: robot_blocks and
robot_friend_requests (created in the baseline) had no generated tables, the
feedback_messages model was missing app_version/browser_tz (added in 00003 and
00004), and UseSchema omitted account_best_move and the two robot tables.
Regenerate so the jet layer mirrors the migrations again.

Additive only — two nullable columns appended to feedback_messages plus two new
tables; the full build, vet, unit and integration suites stay green.

backend/internal/postgres/jet/backend/model/robot_friend_requests.go

@@ -0,0 +1,23 @@
+//
+// Code generated by go-jet DO NOT EDIT.
+//
+// WARNING: Changes to this file may cause incorrect behavior
+// and will be lost if the code is regenerated
+//
+
+package model
+
+import (
+	"github.com/google/uuid"
+	"time"
+)
+
+type RobotFriendRequests struct {
+	ID          uuid.UUID `sql:"primary_key"`
+	RequesterID uuid.UUID
+	GameID      uuid.UUID
+	Seat        int16
+	RobotID     uuid.UUID
+	DisplayName string
+	CreatedAt   time.Time
+}