fix: parse MCP result payloads and drop place idempotency_key

Typed result structs replace empty envelopes. Equity place sends
ref_id only so live additionalProperties:false schemas accept the call.

watchlists/watchlists.go

@@ -63,14 +63,26 @@ type ItemsResult struct {
 // OptionListRequest is the argument set for get_option_watchlist (none).
 type OptionListRequest struct{}
 
+// OptionWatchItem is one contract on the options watchlist.
+type OptionWatchItem struct {
+	OptionID     string
+	Symbol       string
+	Title        string
+	PositionType string
+}
+
 // OptionListResult is the parsed get_option_watchlist payload.
-type OptionListResult struct{}
+type OptionListResult struct {
+	Items []OptionWatchItem
+}
 
 // PopularRequest is the argument set for get_popular_watchlists (none).
 type PopularRequest struct{}
 
 // PopularResult is the parsed get_popular_watchlists payload.
-type PopularResult struct{}
+type PopularResult struct {
+	Watchlists []Watchlist
+}
 
 // CreateRequest is the argument set for create_watchlist.
 type CreateRequest struct {