Stage 7 (wip): docs bake + stage renumber (insert UI Stage 8, shift +1)

- PLAN.md: new Stage 8 (UI social/account/history); Telegram->9, Admin->10, Linking->11, Polish->12; tracker + Stage 7 refinements; split the Stage 6 'wired in Stage 7' note between 7 and 8
- ARCHITECTURE: promote ui to current (slice scope, board-replay, codegen, theming, mock)
- FUNCTIONAL(+ru): client-app section with the Stage 7/8 split
- README + ui/README + CLAUDE.md: UI build/run/test, codegen, pnpm notes
- bumped Stage 8-11 refs (+1) across docs and code comments

backend/internal/game/types.go

@@ -15,7 +15,7 @@ const (
 	StatusFinished = "finished"
 )
 
-// ComplaintStatus values; Stage 9 owns the resolution lifecycle, Stage 3 only
+// ComplaintStatus values; Stage 10 owns the resolution lifecycle, Stage 3 only
 // ever writes StatusComplaintOpen.
 const StatusComplaintOpen = "open"
 
@@ -176,7 +176,7 @@ type RobotTurn struct {
 	Seed          int64
 }
 
-// Complaint is a word-check complaint awaiting admin review (Stage 9).
+// Complaint is a word-check complaint awaiting admin review (Stage 10).
 type Complaint struct {
 	ID            uuid.UUID
 	ComplainantID uuid.UUID