feat(admin): grant hints to a user's wallet from the console

Add an "Add hints" form on the admin user card that additively tops up a
player's hint wallet (1-100 per grant). The grant is raise-only by
construction (an additive UPDATE never lowers the balance) and stays correct
under a concurrent in-game spend; a per-grant cap bounds a fat-finger, since
the console can never reduce a wallet.

The in-game hint policy is unchanged and already correct: a game offers the
per-seat allowance plus the wallet, spending the allowance first and the
wallet only after (covered by TestHintPolicy).

docs/FUNCTIONAL.md

@@ -220,3 +220,8 @@ is blocked"* (permanent) or *"…blocked until <date, time>"* (temporary,
 plus the reason when one was given, and the app stops all background traffic with the server. A
 temporary block lifts itself when it expires; the operator can also **unblock** from the user card
 at any time (games already lost stay lost).
+
+From the user card the operator can also **top up a player's hint wallet**: an additive grant
+(1–100 hints per action) that raises the balance shown on the card. Grants are **raise-only** —
+the console can never lower a wallet (a player only loses hints by spending them in a game), so an
+over-grant cannot be reversed there.