refactor(memory)!: 块 union 化，彻底淘汰 CAS 第一阶段（生产代码）

块自带负载（MemoryBlock.Data），删 PayloadDigest；检索纯向量，媒体随块
同生灭。生产代码全绿；CAS 专属测试将在下一提交随判据重写。

- memory: Data BLOB + migration9；blockColumns 不含 data（召回只比向量）；
  MediaBlockID 内容派生 ID；BlockByIDPrefix/BlockData 按需加载
- sdk: memory_impl 去 media.Store；MemoryBlockView PayloadDigest→HasData
- core: mediaref/graphmedia/crossmodal/medialoop 全部改块语义；
  captureBlockMedia 直接产块；resolveMediaRefs 按块 ID 解析
- knowledge: 媒体字节随条目目录自带（File+Data），删 mediaGet/mediaPut
- webui: graphBlockView/pulse payload_digest→has_data
- bootstrap/registry: 去 MediaStore 接线（SetMediaStore 空实现，待⑥删包）

internal/plugins/webui/handler_graph_pulse_test.go

@@ -44,7 +44,7 @@ func (f *fakeGraphMemory) BlocksChangedSince(since time.Time, limit int) ([]sdk.
 		}
 		out = append(out, sdk.MemoryBlockView{
 			ID: b.ID, Modality: string(b.Modality), Text: b.Text,
-			PayloadDigest: b.PayloadDigest, MIME: b.MIME,
+			HasData: len(b.Data) > 0, MIME: b.MIME,
 			Source: b.Source, Tool: b.Tool, Scene: b.Scene,
 			CreatedAt: b.CreatedAt, UpdatedAt: b.UpdatedAt,
 		})
@@ -74,10 +74,10 @@ func graphFixture() map[string]interface{} {
 		//   修复前 pulse 读的是它，而它永远落在窗口外 ⇒ 恒返回空。
 		"memory_blocks": []memory.MemoryBlock{
 			{ID: "b_old", Modality: memory.BlockModality("text"), Text: "老块",
-				PayloadDigest: "d0", Vector: []float64{0.1, 0.2, 0.3},
+				Vector: []float64{0.1, 0.2, 0.3},
 				CreatedAt: old, UpdatedAt: now.Add(-8 * time.Hour)},
 			{ID: "b_new", Modality: memory.BlockModality("text"), Text: "刚学到的东西",
-				PayloadDigest: "d1", Vector: []float64{0.1, 0.2, 0.3},
+				Vector: []float64{0.1, 0.2, 0.3},
 				CreatedAt: now, UpdatedAt: now},
 		},
 	}
@@ -226,7 +226,7 @@ func TestGraphPulse_IgnoresFrozenLegacyNodes(t *testing.T) {
 		// 块表：有一条刚更新（活图谱的真实形态）
 		"memory_blocks": []memory.MemoryBlock{
 			{ID: "b_live", Modality: memory.BlockModality("text"), Text: "刚写入的块",
-				PayloadDigest: "dx", CreatedAt: now, UpdatedAt: now},
+				CreatedAt: now, UpdatedAt: now},
 		},
 	}
 

internal/plugins/webui/handler_memory.go

@@ -127,20 +127,20 @@ func (h *Handler) handleMemoryTools(w http.ResponseWriter, r *http.Request) {
 // 所以这里显式裁掉 vector，而不是让 GraphData 返回值带个开关：
 // 本接口的语义就是「图谱的可视化数据」，让唯一调用方拿到它要的东西。
 type graphBlockView struct {
-	ID            string    `json:"id"`
-	Modality      string    `json:"modality"`
-	Text          string    `json:"text,omitempty"`
-	PayloadDigest string    `json:"payload_digest"`
-	MIME          string    `json:"mime,omitempty"`
-	Size          int64     `json:"size"`
-	Width         int       `json:"width,omitempty"`
-	Height        int       `json:"height,omitempty"`
-	Fingerprint   string    `json:"fingerprint,omitempty"`
-	Source        string    `json:"source,omitempty"`
-	Tool          string    `json:"tool,omitempty"`
-	Scene         string    `json:"scene,omitempty"`
-	CreatedAt     time.Time `json:"created_at"`
-	UpdatedAt     time.Time `json:"updated_at"`
+	ID          string    `json:"id"`
+	Modality    string    `json:"modality"`
+	Text        string    `json:"text,omitempty"`
+	HasData     bool      `json:"has_data"`
+	MIME        string    `json:"mime,omitempty"`
+	Size        int64     `json:"size"`
+	Width       int       `json:"width,omitempty"`
+	Height      int       `json:"height,omitempty"`
+	Fingerprint string    `json:"fingerprint,omitempty"`
+	Source      string    `json:"source,omitempty"`
+	Tool        string    `json:"tool,omitempty"`
+	Scene       string    `json:"scene,omitempty"`
+	CreatedAt   time.Time `json:"created_at"`
+	UpdatedAt   time.Time `json:"updated_at"`
 }
 
 // graphDataForVisual 把 GraphData 的原始 map 裁成可视化视图（去掉稠密向量）。
@@ -162,20 +162,20 @@ func graphDataForVisual(data map[string]interface{}) map[string]interface{} {
 	for i := range blocks {
 		b := blocks[i]
 		views = append(views, graphBlockView{
-			ID:            b.ID,
-			Modality:      string(b.Modality),
-			Text:          b.Text,
-			PayloadDigest: b.PayloadDigest,
-			MIME:          b.MIME,
-			Size:          b.Size,
-			Width:         b.Width,
-			Height:        b.Height,
-			Fingerprint:   b.Fingerprint,
-			Source:        b.Source,
-			Tool:          b.Tool,
-			Scene:         b.Scene,
-			CreatedAt:     b.CreatedAt,
-			UpdatedAt:     b.UpdatedAt,
+			ID:          b.ID,
+			Modality:    string(b.Modality),
+			Text:        b.Text,
+			HasData:     len(b.Data) > 0,
+			MIME:        b.MIME,
+			Size:        b.Size,
+			Width:       b.Width,
+			Height:      b.Height,
+			Fingerprint: b.Fingerprint,
+			Source:      b.Source,
+			Tool:        b.Tool,
+			Scene:       b.Scene,
+			CreatedAt:   b.CreatedAt,
+			UpdatedAt:   b.UpdatedAt,
 		})
 	}
 	out["memory_blocks"] = views
@@ -243,16 +243,16 @@ func (h *Handler) handleMemoryGraphPulse(w http.ResponseWriter, r *http.Request)
 	pulse := make([]map[string]interface{}, 0, len(blocks))
 	for _, b := range blocks {
 		pulse = append(pulse, map[string]interface{}{
-			"id":             b.ID,
-			"name":           b.Text,
-			"modality":       string(b.Modality),
-			"payload_digest": b.PayloadDigest,
-			"mime":           b.MIME,
-			"tool":           b.Tool,
-			"scene":          b.Scene,
-			"source":         b.Source,
-			"updated_at":     b.UpdatedAt,
-			"created_at":     b.CreatedAt,
+			"id":         b.ID,
+			"name":       b.Text,
+			"modality":   b.Modality,
+			"has_data":   b.HasData,
+			"mime":       b.MIME,
+			"tool":       b.Tool,
+			"scene":      b.Scene,
+			"source":     b.Source,
+			"updated_at": b.UpdatedAt,
+			"created_at": b.CreatedAt,
 		})
 	}
 	writeJSON(w, http.StatusOK, map[string]interface{}{