refactor: rename action→activity, statemachine→workflow, remove HTTP API layer

- action/ → activity/ (Temporal activities)
- statemachine/ → workflow/ (Temporal workflows)
- Removed internal/api/ and cmd/server/ (api-gw handles HTTP, Temporal is the API)
- Created pkg/types/types.go as single source of truth for all shared types
- Extracted CallRoleLLM helper (DRY: implementer/planner/judge shared pattern)
- Fixed circular import: workflow_graph_query uses string activity names
- Fixed logger.logf → logger.Info/Warn (method didn't exist)
- Fixed routing types: added Branches, Activity, BackoffSeconds, TaskActivity
- Fixed db.Canvas.Name, db.Client→DB, GetWorkflow→FetchWorkflow
- Removed unused imports
- All tests pass, build clean, vet clean

activity/query_graph_rag.go

@@ -0,0 +1,101 @@
+package activity
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+	"time"
+)
+
+// QueryGraphRAGActivity queries Memory System for semantic relations
+func QueryGraphRAGActivity(ctx context.Context, input GraphRAGQueryInput) (GraphRAGQueryOutput, error) {
+	logger := newActivityLogger(ctx)
+	output := GraphRAGQueryOutput{
+		WorkflowID: input.WorkflowID,
+		Query:      input.Query,
+		Edges:      []EdgeWithWording{},
+		Paths:      []QueryPathData{},
+	}
+
+	logger.Info("Querying GraphRAG: %s", input.Query)
+
+	// Get Memory Service URL from env
+	memoryURL := os.Getenv("MEMORY_SERVICE_URL")
+	if memoryURL == "" {
+		memoryURL = "http://localhost:8000"
+	}
+
+	// Build payload for Memory System
+	payload := map[string]interface{}{
+		"workflow_id":      input.WorkflowID,
+		"query":            input.Query,
+		"search_type":      input.SearchType,
+		"relation_type":    input.RelationType,
+		"confidence_floor": input.ConfidenceFloor,
+		"top_k":            input.TopK,
+		"ranking_profile":  input.RankingProfile,
+		"canvas_nodes":     input.Canvas.Nodes,
+		"canvas_edges":     input.Canvas.Edges,
+		"relations":        input.Canvas.Relations,
+	}
+
+	reqBody, err := json.Marshal(payload)
+	if err != nil {
+		return output, fmt.Errorf("failed to marshal payload: %w", err)
+	}
+
+	// Call Memory System unified query endpoint
+	req, err := http.NewRequestWithContext(
+		ctx,
+		"POST",
+		memoryURL+"/workflows/query",
+		bytes.NewReader(reqBody),
+	)
+	if err != nil {
+		return output, fmt.Errorf("failed to create request: %w", err)
+	}
+
+	req.Header.Set("Content-Type", "application/json")
+	if token := ctx.Value("jwt_token"); token != nil {
+		req.Header.Set("Authorization", fmt.Sprintf("Bearer %v", token))
+	}
+
+	startTime := time.Now()
+	client := &http.Client{Timeout: 30 * time.Second}
+	resp, err := client.Do(req)
+	if err != nil {
+		return output, fmt.Errorf("failed to call Memory Service: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != 200 {
+		body, _ := io.ReadAll(resp.Body)
+		return output, fmt.Errorf("Memory Service returned %d: %s", resp.StatusCode, string(body))
+	}
+
+	// Parse response
+	var graphResp struct {
+		Edges      []EdgeWithWording `json:"edges"`
+		Paths      []QueryPathData   `json:"paths"`
+		TotalCount int               `json:"total_count"`
+		HasMore    bool              `json:"has_more"`
+	}
+
+	if err := json.NewDecoder(resp.Body).Decode(&graphResp); err != nil {
+		return output, fmt.Errorf("failed to decode response: %w", err)
+	}
+
+	output.Edges = graphResp.Edges
+	output.Paths = graphResp.Paths
+	output.TotalCount = graphResp.TotalCount
+	output.HasMore = graphResp.HasMore
+	output.ExecutionMs = time.Since(startTime).Milliseconds()
+
+	logger.Info("GraphRAG returned %d edges, %d paths in %dms", 
+		len(output.Edges), len(output.Paths), output.ExecutionMs)
+	return output, nil
+}