chore(v2): vendor dependencies for offline/China builds

go mod vendor pins onnxruntime_go v1.12.1, Gio and the rest into v2/vendor
so go run/build work without hitting proxy.golang.org (blocked/slow in
China). Verified: CGO_ENABLED=1 go build -mod=vendor ./internal/spike and
GOOS=windows go build -mod=vendor ./internal/ui both pass.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

v2/vendor/gioui.org/io/transfer/transfer.go

@@ -0,0 +1,95 @@
+// Package transfer contains operations and events for brokering data transfers.
+//
+// The transfer protocol is as follows:
+//
+//   - Data sources use [SourceFilter] to receive an [InitiateEvent] when a drag
+//     is initiated, and an [RequestEvent] for each initiation of a data transfer.
+//     Sources respond to requests with [OfferCmd].
+//   - Data targets use [TargetFilter] to receive an [DataEvent] for receiving data.
+//     The target must close the data event after use.
+//
+// When a user initiates a pointer-guided drag and drop transfer, the
+// source as well as all potential targets receive an InitiateEvent.
+// Potential targets are targets with at least one MIME type in common
+// with the source. When a drag gesture completes, a CancelEvent is sent
+// to the source and all potential targets.
+//
+// Note that the RequestEvent is sent to the source upon drop.
+package transfer
+
+import (
+	"io"
+
+	"gioui.org/io/event"
+)
+
+// OfferCmd is used by data sources as a response to a RequestEvent.
+type OfferCmd struct {
+	Tag event.Tag
+	// Type is the MIME type of Data.
+	// It must be the Type from the corresponding RequestEvent.
+	Type string
+	// Data contains the offered data. It is closed when the
+	// transfer is complete or cancelled.
+	// Data must be kept valid until closed, and it may be used from
+	// a goroutine separate from the one processing the frame.
+	Data io.ReadCloser
+}
+
+func (OfferCmd) ImplementsCommand() {}
+
+// SourceFilter filters for any [RequestEvent] that match a MIME type
+// as well as [InitiateEvent] and [CancelEvent].
+// Use multiple filters to offer multiple types.
+type SourceFilter struct {
+	// Target is a tag included in a previous event.Op.
+	Target event.Tag
+	// Type is the MIME type supported by this source.
+	Type string
+}
+
+// TargetFilter filters for any [DataEvent] whose type matches a MIME type
+// as well as [CancelEvent]. Use multiple filters to accept multiple types.
+type TargetFilter struct {
+	// Target is a tag included in a previous event.Op.
+	Target event.Tag
+	// Type is the MIME type accepted by this target.
+	Type string
+}
+
+// RequestEvent requests data from a data source. The source must
+// respond with an OfferCmd.
+type RequestEvent struct {
+	// Type is the first matched type between the source and the target.
+	Type string
+}
+
+func (RequestEvent) ImplementsEvent() {}
+
+// InitiateEvent is sent to a data source when a drag-and-drop
+// transfer gesture is initiated.
+//
+// Potential data targets also receive the event.
+type InitiateEvent struct{}
+
+func (InitiateEvent) ImplementsEvent() {}
+
+// CancelEvent is sent to data sources and targets to cancel the
+// effects of an InitiateEvent.
+type CancelEvent struct{}
+
+func (CancelEvent) ImplementsEvent() {}
+
+// DataEvent is sent to the target receiving the transfer.
+type DataEvent struct {
+	// Type is the MIME type of Data.
+	Type string
+	// Open returns the transfer data. It is only valid to call Open in the frame
+	// the DataEvent is received. The caller must close the return value after use.
+	Open func() io.ReadCloser
+}
+
+func (DataEvent) ImplementsEvent() {}
+
+func (SourceFilter) ImplementsFilter() {}
+func (TargetFilter) ImplementsFilter() {}