feat(admin): admin grant — raw benefits and by-product reward bundles

The /_gm user card gains a Grant panel: grant raw benefit atoms (hints /
no-ads days / forever) or a defined value product (a reward bundle, including
an archived one), origin-picked. Both write an admin_grant ledger row via
payments.Grant / GrantProduct; the by-product grant records the source
product_id + snapshot. Both refuse a chips atom (never grant currency) or a
tournament atom (no credit target yet); chips/tournament products are also
kept out of the by-product picker.

Tests: the console grant end to end (raw, by-product, refuse a chips pack,
CSRF-guarded).

backend/internal/adminconsole/views.go

@@ -198,6 +198,9 @@ type UserDetailView struct {
 	// Finance is the account's payments picture (balances, benefits, refund risk, ledger). Present
 	// is false when the payments domain is unwired.
 	Finance FinanceView
+	// Grant is the admin-grant panel (origin picker + grantable products). Present is false when the
+	// payments domain is unwired.
+	Grant GrantFormView
 }
 
 // FinanceView is the account's payments picture on the user card: chip balances per funding
@@ -701,3 +704,21 @@ type ProductFormView struct {
 	PriceChip  int64
 	Transacted bool
 }
+
+// GrantFormView is the admin-grant panel on the user card: the origin picker and the grantable
+// products (value bundles — hints / no-ads days — including archived ones; chips and tournament
+// products are excluded). Present is false when the payments domain is unwired.
+type GrantFormView struct {
+	Present  bool
+	Origins  []string
+	Products []GrantProductOption
+}
+
+// GrantProductOption is one grantable product in the by-product picker: its id, title, an atom
+// summary, and whether it is archived (the common case for a non-public reward bundle).
+type GrantProductOption struct {
+	ID       string
+	Title    string
+	Summary  string
+	Archived bool
+}