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/lobby/lobby.go

@@ -12,6 +12,7 @@ import (
 
 	"github.com/google/uuid"
 
+	"scrabble/backend/internal/engine"
 	"scrabble/backend/internal/game"
 )
 
@@ -25,7 +26,7 @@ type GameCreator interface {
 // auto-match. robot.Service satisfies it; it returns an error when no robot is
 // available so the matchmaker can defer substitution.
 type RobotProvider interface {
-	Pick() (uuid.UUID, error)
+	Pick(variant engine.Variant) (uuid.UUID, error)
 }
 
 // Blocker reports whether two accounts have a block between them (either