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/services/gateway/ws_bridge.go

@@ -4,6 +4,7 @@ import (
 	"strings"
 
 	"git.yeij.top/AskaEth/Cyrene_v2/internal/bus"
+	"git.yeij.top/AskaEth/Cyrene_v2/internal/runtime/model"
 	"git.yeij.top/AskaEth/Cyrene_v2/internal/runtime/orchestration"
 	"git.yeij.top/AskaEth/Cyrene_v2/internal/runtime/orchestration/comm"
 )
@@ -79,6 +80,38 @@ func subagentProgressEvent(e bus.Event) (wsEvent, bool) {
 	}}, true
 }
 
+// streamEventData maps a streamed model.StreamKind to its downstream WS event
+// type and builds a typed data payload. It is what turns the loop's structured
+// events into the message.*/thinking.*/tool_call.*/tool_execution.* frames the
+// frontend renders. Unknown kinds fall back to the legacy stream_chunk shape so
+// an unrecognized event still reaches the client instead of being dropped.
+func streamEventData(ev model.StreamEvent) (string, map[string]any) {
+	switch ev.Kind {
+	case model.StreamKindTextStart:
+		return "message.start", map[string]any{"index": ev.Index}
+	case model.StreamKindTextDelta:
+		return "message.delta", map[string]any{"delta": ev.Delta, "index": ev.Index}
+	case model.StreamKindTextEnd:
+		return "message.end", map[string]any{"index": ev.Index}
+	case model.StreamKindThinkingStart:
+		return "thinking.start", map[string]any{"index": ev.Index}
+	case model.StreamKindThinkingDelta:
+		return "thinking.delta", map[string]any{"delta": ev.Delta, "index": ev.Index}
+	case model.StreamKindThinkingEnd:
+		return "thinking.end", map[string]any{"index": ev.Index}
+	case model.StreamKindToolCallStart:
+		return "tool_call.start", map[string]any{"id": ev.ID, "index": ev.Index}
+	case model.StreamKindToolCallDelta:
+		return "tool_call.delta", map[string]any{"id": ev.ID, "index": ev.Index, "delta": ev.Delta}
+	case model.StreamKindToolCallEnd:
+		return "tool_call.end", map[string]any{"id": ev.ID, "index": ev.Index}
+	case model.StreamKindToolExecution:
+		return "tool_execution.update", map[string]any{"id": ev.ID, "index": ev.Index, "delta": ev.Delta}
+	default:
+		return "stream_chunk", map[string]any{"delta": ev.Delta}
+	}
+}
+
 // isBroadcastAgentEvent reports whether subject has the exact 4-token broadcast
 // shape cyrene.agent.<from>.event, which is how the scheduler publishes progress.
 // It deliberately does not match addressed events (cyrene.agent.<from>.<to>.event)