Stage 7 polish: docs + mark Stage 7 done (Part H)

- new docs/UI_DESIGN.md (design system: shell, nav, tab-bar, tiles, board zoom/labels, HoldConfirm, banner rotator, result iconography)
- ARCHITECTURE: app-shell + announcement channel (mock->server) + hint place-on-board / no_hint_available contract + board-style setting
- FUNCTIONAL(+ru): hint-on-board, word-check constraints/throttle, board style
- PLAN: Stage 7 -> done + polish refinement note; CLAUDE sources list

docs/FUNCTIONAL.md

@@ -17,7 +17,10 @@ the top-1 hint, the unlimited word-check with complaint, per-game chat and nudge
 real-time in-app updates, switching interface language (en/ru) and theme, and a
 read-only profile. Managing friends and blocks, creating friend games (invitations),
 editing the profile, the statistics screen and the history/GCG viewer arrive in
-Stage 8.
+Stage 8. Settings also pick the board's bonus-label style (beginner / classic /
+none). A hint **lays the suggested tiles on the board** for the player to confirm and
+costs nothing when the rack has no legal move. The word-check accepts only the
+variant's alphabet, remembers answers within the session and rate-limits repeats.
 
 ### Identity & sessions *(Stage 1 / 6)*
 A player arrives from a platform (Telegram first), via email login, or as an