chore(ui): change hints symbol for backward unicode compatibility

docs/FUNCTIONAL.md

@@ -50,7 +50,7 @@ tail — at a real control, and a **tap anywhere** advances to the next; after t
 overlay is gone for good. Two independent series run. The **lobby** series points at the
 ⚙️ settings, ✏️ statistics and 🎲 new-game tabs. The **game** series, on the player's first game
 board, points at the scoreboard header (move history / chat / word-check), the 🔄 pass-and-exchange,
-🛟 hints and 🔀 shuffle controls, and the rack. A series counts as seen only **after its last hint**,
+✨ hints and 🔀 shuffle controls, and the rack. A series counts as seen only **after its last hint**,
 so leaving mid-way replays it from the start next time; it is remembered per device. Arriving at the
 lobby is the lobby trigger, so a player who deep-links straight into Settings → Friends still gets the
 lobby walk-through on their first trip back. Both series work the same in portrait and landscape (the