Stage 17: backend defect fixes (nudge code, TG name, robot names/timing, multi-device push, move-duration metric + admin analytics)

- #3 nudge-on-own-turn: distinct result code nudge_own_turn + i18n (was reused 'not_your_turn')
- #2 sanitize connector registration name to the editable format; Player/Игрок-XXXXX fallback
- #5 variant-aware robot name pools (composed full/colloquial first + surname forms; ru gets <=20% latin)
- #4 move-number-aware robot move timing (early 1-5min -> late 10-90min, skew k=4)
- #7 emit move event to the actor too (multi-device sync); opponent_moved stays in-app only
- #1 live game_move_duration{variant,phase} histogram + admin console per-user min/avg/max columns and an inline-SVG move-time-by-move-number chart (offline from the journal)
- ProvisionRobot bypasses editor name validation (system names like 'Peter J.')

backend/internal/server/handlers.go

@@ -148,8 +148,10 @@ func statusForError(err error) (int, string) {
 		return http.StatusNotFound, "not_found"
 	case errors.Is(err, game.ErrNotAPlayer), errors.Is(err, social.ErrNotParticipant):
 		return http.StatusForbidden, "not_a_player"
-	case errors.Is(err, game.ErrNotYourTurn), errors.Is(err, social.ErrNudgeOnOwnTurn):
+	case errors.Is(err, game.ErrNotYourTurn):
 		return http.StatusConflict, "not_your_turn"
+	case errors.Is(err, social.ErrNudgeOnOwnTurn):
+		return http.StatusConflict, "nudge_own_turn"
 	case errors.Is(err, game.ErrFinished), errors.Is(err, social.ErrGameNotActive):
 		return http.StatusConflict, "game_finished"
 	case errors.Is(err, game.ErrGameActive):