feat(admin): manual account blocking (suspensions)

Operator-driven hard block, the counterpart to the soft high-rate flag: permanent or until a date, with an optional reason chosen from an editable en+ru picklist (snapshotted onto the block). A block forfeits the player's active games (opponent wins, as a resignation) and cancels their open matchmaking games. A backend gate refuses a blocked account on every /api/v1/user/* route except the block-status probe with 403 account_blocked, which threads through the gateway as the Execute result_code; the UI surfaces it as a terminal blocked screen and stops all push/poll. Temporary blocks self-expire; the operator can unblock at any time (lost games stay lost). Sessions are not revoked, so the blocked client can still reach the exempt block-status endpoint.

Backend: migration 00003 (account_suspensions + suspension_reasons) + jet regen; account suspension store; game.ForfeitAllForAccount; requireNotSuspended gate + block-status endpoint; admin console block/unblock + Reasons CRUD. Wire: fbs BlockStatus + account.block_status gateway op. UI: blocked screen, app state, transport/codec, i18n. Docs: ARCHITECTURE, FUNCTIONAL(+ru), PRERELEASE (AB).

backend/internal/adminconsole/views.go

@@ -135,6 +135,29 @@ type UserDetailView struct {
 	// MoveChart is the pre-rendered inline SVG of the account's per-move-number think
 	// time (min/mean/max), empty when the account has no timed move.
 	MoveChart template.HTML
+	// Suspension is the account's current manual-block state, shown with the block/unblock
+	// form; Reasons is the operator-editable reason picklist offered in the block form.
+	Suspension SuspensionView
+	Reasons    []ReasonOption
+}
+
+// SuspensionView is an account's current manual-block state shown on the user card: whether it
+// is blocked, whether the block is permanent, the pre-formatted expiry (empty when permanent),
+// when it was applied, and the reason snapshot in both languages (empty when none was cited).
+type SuspensionView struct {
+	Blocked   bool
+	Permanent bool
+	Until     string
+	BlockedAt string
+	ReasonEn  string
+	ReasonRu  string
+}
+
+// ReasonOption is one suspension-reason picklist entry offered in the block form's dropdown.
+type ReasonOption struct {
+	ID     string
+	TextEn string
+	TextRu string
 }
 
 // StatsRow is an account's lifetime statistics.
@@ -317,6 +340,19 @@ type FlaggedAccountRow struct {
 	FlaggedAt   string
 }
 
+// ReasonsView is the suspension-reason picklist management page: every editable reason entry.
+type ReasonsView struct {
+	Items []ReasonRow
+}
+
+// ReasonRow is one editable suspension-reason entry, with its English and Russian text.
+type ReasonRow struct {
+	ID        string
+	TextEn    string
+	TextRu    string
+	CreatedAt string
+}
+
 // MessageView is the result page shown after a POST action.
 type MessageView struct {
 	Heading string