fix: bind Cua pixel actions to current screenshot geometry

Correct native scroll scaling, reject stale or out-of-bounds pixel targets, and scope DPI awareness to geometry reads. Package adapter 0.36.0+artemis.3 and document the high-effort cross-device verification.

Validation: Go tests and vet, packaged MCP schema and handshake, Python checks, and user-run high-effort task completed with a passed verdict and explicit coverage limits.

plugins/cua-driver/main_test.go

@@ -101,7 +101,7 @@ func TestInputContractsHaveOneTargetingMode(t *testing.T) {
 		"press_key": {"pid": 1, "window_id": 2, "key": "t", "modifiers": []any{"ctrl"}, "delivery_mode": "foreground"},
 		"type_text": {"pid": 1, "window_id": 2, "text": "中文"},
 		"set_value": {"pid": 1, "window_id": 2, "element_token": "s00000001:9", "value": "value"},
-		"scroll":    {"pid": 1, "window_id": 2, "direction": "down", "x": 100, "y": 100},
+		"scroll":    {"pid": 1, "window_id": 2, "direction": "down", "x": 100, "y": 100, "capture_id": "current"},
 	} {
 		if err := a.validate(name, args); err != nil {
 			t.Fatalf("valid %s: %v", name, err)