Stage 10: admin console & dictionary ops (complaint review, hot-reload, broadcasts)

Server-rendered admin console in the backend at /_gm (internal/adminconsole),
fronted on the gateway's public listener by Basic-Auth + a verbatim reverse proxy
(mounted on the edge mux below the h2c wrap). A same-origin check guards its POSTs;
no operator identity is tracked. This supersedes the Stage 6 gateway-fronts-
/api/v1/admin model: GATEWAY_ADMIN_ADDR and the backend /api/v1/admin ping are
dropped and gateway/internal/admin is repurposed to the verbatim proxy.

- Complaints: migration 00008 (+ jetgen) adds disposition/resolution_note/
  resolved_at/applied_in_version + the deferred status CHECK; resolution feeds a
  query-derived pending dictionary-change pipeline (marked applied after a reload).
- Dictionary hot-reload: per-version subdir BACKEND_DICT_DIR/<version>/ via the new
  Registry.LoadAvailable; engine.OpenWithVersions restores resident versions on
  restart. Partially addresses TODO-2.
- Broadcasts: a backend Telegram-connector client (internal/connector,
  BACKEND_CONNECTOR_ADDR) for SendToUser / SendToGameChannel (discharges the Stage 9
  forward-note).
- Admin reads: account.ListAccounts/CountAccounts/Identities and
  game.ListGames/CountGames/GameByID/ListComplaints/GetComplaint/CountComplaints/
  ResolveComplaint/DictionaryChanges/MarkChangesApplied.
- Tests: adminconsole render, engine reload, same-origin guard, gateway verbatim
  proxy + h2c console mount, inttest complaint pipeline + list/count + /_gm console.
- Docs: PLAN (Stage 10 done + refinements + TODO-2), ARCHITECTURE §1/§5/§6/§12/§13,
  FUNCTIONAL (+_ru), TESTING, backend/gateway READMEs.

backend/internal/account/account.go

@@ -67,6 +67,16 @@ type Account struct {
 	UpdatedAt              time.Time
 }
 
+// Identity is one of an account's platform/email identities, surfaced on the
+// admin account-detail view. ExternalID is the platform user id (or the email
+// address for an email identity); Confirmed tracks the email confirm-code flow.
+type Identity struct {
+	Kind       string
+	ExternalID string
+	Confirmed  bool
+	CreatedAt  time.Time
+}
+
 // Store is the Postgres-backed query surface for accounts and identities.
 type Store struct {
 	db *sql.DB
@@ -187,6 +197,54 @@ func (s *Store) IdentityExternalID(ctx context.Context, accountID uuid.UUID, kin
 	return row.ExternalID, nil
 }
 
+// Identities returns the account's platform/email identities, oldest first, for
+// the admin account-detail view.
+func (s *Store) Identities(ctx context.Context, accountID uuid.UUID) ([]Identity, error) {
+	stmt := postgres.SELECT(table.Identities.AllColumns).
+		FROM(table.Identities).
+		WHERE(table.Identities.AccountID.EQ(postgres.UUID(accountID))).
+		ORDER_BY(table.Identities.CreatedAt.ASC())
+	var rows []model.Identities
+	if err := stmt.QueryContext(ctx, s.db, &rows); err != nil {
+		return nil, fmt.Errorf("account: list identities %s: %w", accountID, err)
+	}
+	out := make([]Identity, 0, len(rows))
+	for _, r := range rows {
+		out = append(out, Identity{Kind: r.Kind, ExternalID: r.ExternalID, Confirmed: r.Confirmed, CreatedAt: r.CreatedAt})
+	}
+	return out, nil
+}
+
+// ListAccounts returns accounts for the admin user list, newest first, paginated
+// by limit and offset.
+func (s *Store) ListAccounts(ctx context.Context, limit, offset int) ([]Account, error) {
+	stmt := postgres.SELECT(table.Accounts.AllColumns).
+		FROM(table.Accounts).
+		ORDER_BY(table.Accounts.CreatedAt.DESC()).
+		LIMIT(int64(limit)).
+		OFFSET(int64(offset))
+	var rows []model.Accounts
+	if err := stmt.QueryContext(ctx, s.db, &rows); err != nil {
+		return nil, fmt.Errorf("account: list accounts: %w", err)
+	}
+	out := make([]Account, 0, len(rows))
+	for _, r := range rows {
+		out = append(out, modelToAccount(r))
+	}
+	return out, nil
+}
+
+// CountAccounts returns the total number of accounts, for admin-list pagination.
+func (s *Store) CountAccounts(ctx context.Context) (int, error) {
+	stmt := postgres.SELECT(postgres.COUNT(table.Accounts.AccountID).AS("count")).
+		FROM(table.Accounts)
+	var dest struct{ Count int64 }
+	if err := stmt.QueryContext(ctx, s.db, &dest); err != nil {
+		return 0, fmt.Errorf("account: count accounts: %w", err)
+	}
+	return int(dest.Count), nil
+}
+
 // findByIdentity joins identities to accounts and returns the matching account,
 // or ErrNotFound.
 func (s *Store) findByIdentity(ctx context.Context, kind, externalID string) (Account, error) {