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/ARCHITECTURE.md

@@ -477,7 +477,9 @@ English game the Latin pool.
   Migrations are embedded SQL applied with `pressly/goose/v3` at startup. Primary
   keys are application-generated **UUIDv7**.
 - Tables: `accounts` (durable internal accounts, carrying the away-window
-  columns `away_start`/`away_end`, the hint wallet `hint_balance`, the `is_guest`
+  columns `away_start`/`away_end`, the hint wallet `hint_balance` (spent after a
+  game's per-seat allowance; an operator tops it up with an additive, raise-only
+  grant from the admin console), the `is_guest`
   flag for ephemeral guest rows, the `notifications_in_app_only` out-of-app push
   toggle, the `paid_account` service flag and the merge-tombstone columns
   `merged_into`/`merged_at`),