feat(model): Top5#1 结构化流事件 + WS 事件体系（对齐 OpenClaw AssistantMessageEvent）

- 新增 model/stream.go：StreamKind(text/thinking/tool_call 各 start/delta/end + tool_execution)
  + StreamEvent{Kind,Delta,Index,ID}。
- ChatStream 签名 onChunk func(delta string)→onEvent func(StreamEvent)；loop OnStream 同改；
  streamStep 转发结构化事件。
- openai：text_delta + text_start/text_end（正文三段式）；anthropic：文本块 text_*/tool_call_*
  按块 Index（content_block_stop 分支）真分段；fallback：有事件即交付。
- ws_hub：wsEvent 壳补 turnId/seq；新增 broadcastStream；streamChat 每帧打 turnId+seq；
  stream.go 把事件 publish 到 bus ws.stream。
- ws_bridge：streamEventData 映射 text_*→message.start/delta/end、thinking_*→thinking.*、
  tool_call_*→tool_call.*、tool_execution_update→tool_execution.update，未知回退 stream_chunk。
- 前端 ws.ts：解析 message.start/delta/end、thinking.start/delta/end(pendingThinking)、
  tool_call.start/end→addTool、tool_execution.update；保留旧 stream_chunk/thinking/tool_used 兼容；
  types.ts 补 turnId/seq。Docs/api-client.md 增 §3.1 v0.4。

已知限制（注释/文档标注）：turnId 在 OnStream→bus→relay 路径暂为空（StreamEvent 无 turnId 字段，
bus ws.stream 载荷不带 turn）；OpenAI adapter 未解析 tool_call 段；thinking 段两 adapter 暂不发；
tool_execution.update 是保留项（随工具循环钩子后置）。go build/vet/test + 前端 tsc 全绿。

internal/runtime/model/anthropic_stream.go

@@ -52,11 +52,13 @@ type streamBlock struct {
 }
 
 // scanAnthropicSSE incrementally decodes Anthropic's content-block stream. Text
-// deltas are forwarded to onChunk; tool_use input_json_delta fragments are
-// accumulated per block and re-assembled into a structured Args map when the block
-// stops. The stream must terminate with a message_stop event, otherwise ErrStream
-// is returned.
-func scanAnthropicSSE(r io.Reader, onChunk func(string)) (Response, error) {
+// deltas are forwarded as text_delta events (segment bracketed by
+// text_start/text_end); tool_use input_json_delta fragments are forwarded as
+// tool_call_delta events (segment bracketed by tool_call_start/tool_call_end)
+// and accumulated per block so they re-assemble into a structured Args map when
+// the block stops. The stream must terminate with a message_stop event,
+// otherwise ErrStream is returned.
+func scanAnthropicSSE(r io.Reader, onEvent func(StreamEvent)) (Response, error) {
 	scanner := bufio.NewScanner(r)
 	scanner.Buffer(make([]byte, 0, sseBufInit), maxSSELineBytes)
 	agg := Response{}
@@ -78,7 +80,7 @@ func scanAnthropicSSE(r io.Reader, onChunk func(string)) (Response, error) {
 		if err := json.Unmarshal([]byte(data), &evt); err != nil {
 			return Response{}, fmt.Errorf("model: %w: decode stream chunk: %v", ErrUpstream, err)
 		}
-		if err := applyAnthropicEvent(&agg, blocks, &order, &text, evt, onChunk); err != nil {
+		if err := applyAnthropicEvent(&agg, blocks, &order, &text, evt, onEvent); err != nil {
 			return Response{}, err
 		}
 		if evt.Type == "message_stop" {
@@ -102,7 +104,7 @@ func applyAnthropicEvent(
 	order *[]int,
 	text *strings.Builder,
 	evt anthropicStreamEvent,
-	onChunk func(string),
+	onEvent func(StreamEvent),
 ) error {
 	switch evt.Type {
 	case "message_start":
@@ -123,11 +125,21 @@ func applyAnthropicEvent(
 			name:        evt.Content.Name,
 			initialArgs: evt.Content.Input,
 		}
-		if evt.Content.Type == "text" && evt.Content.Text != "" {
-			b.text.WriteString(evt.Content.Text)
-			text.WriteString(evt.Content.Text)
-			if onChunk != nil {
-				onChunk(evt.Content.Text)
+		switch evt.Content.Type {
+		case "text":
+			if onEvent != nil {
+				onEvent(StreamEvent{Kind: StreamKindTextStart, Index: *evt.Index})
+			}
+			if evt.Content.Text != "" {
+				b.text.WriteString(evt.Content.Text)
+				text.WriteString(evt.Content.Text)
+				if onEvent != nil {
+					onEvent(StreamEvent{Kind: StreamKindTextDelta, Delta: evt.Content.Text, Index: *evt.Index})
+				}
+			}
+		case "tool_use":
+			if onEvent != nil {
+				onEvent(StreamEvent{Kind: StreamKindToolCallStart, Index: *evt.Index, ID: evt.Content.ID})
 			}
 		}
 		if _, ok := blocks[*evt.Index]; !ok {
@@ -146,11 +158,31 @@ func applyAnthropicEvent(
 		case "text_delta":
 			b.text.WriteString(evt.Delta.Text)
 			text.WriteString(evt.Delta.Text)
-			if onChunk != nil {
-				onChunk(evt.Delta.Text)
+			if onEvent != nil {
+				onEvent(StreamEvent{Kind: StreamKindTextDelta, Delta: evt.Delta.Text, Index: *evt.Index})
 			}
 		case "input_json_delta":
 			b.input.WriteString(evt.Delta.PartialJSON)
+			if onEvent != nil {
+				onEvent(StreamEvent{Kind: StreamKindToolCallDelta, Delta: evt.Delta.PartialJSON, Index: *evt.Index, ID: b.id})
+			}
+		}
+	case "content_block_stop":
+		if evt.Index == nil {
+			return nil
+		}
+		b := blocks[*evt.Index]
+		if b == nil {
+			return nil
+		}
+		if b.typ == "text" {
+			if onEvent != nil {
+				onEvent(StreamEvent{Kind: StreamKindTextEnd, Index: *evt.Index})
+			}
+		} else if b.typ == "tool_use" {
+			if onEvent != nil {
+				onEvent(StreamEvent{Kind: StreamKindToolCallEnd, Index: *evt.Index, ID: b.id})
+			}
 		}
 	case "message_delta":
 		if evt.Usage != nil {