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

tests/temporal_integration_test.go

@@ -9,7 +9,7 @@ import (
 	"github.com/stretchr/testify/assert"
 	"go.temporal.io/sdk/client"
 	"github.com/rockliang/poimen/workflows/internal/config"
-	"github.com/rockliang/poimen/workflows/statemachine"
+	"github.com/rockliang/poimen/workflows/workflow"
 )
 
 // TestTemporalConnection verifies the worker is connected and healthy
@@ -67,7 +67,7 @@ func TestActivityExecution(t *testing.T) {
 	runResp, err := c.ExecuteWorkflow(ctx, client.StartWorkflowOptions{
 		ID:        workflowID,
 		TaskQueue: "poimen-taskqueue",
-	}, statemachine.TestWorkflow)
+	}, workflow.TestWorkflow)
 
 	assert.NoError(t, err, "failed to execute test workflow")
 	assert.NotNil(t, runResp, "workflow response should not be nil")
@@ -136,28 +136,28 @@ func TestOrchestratorWorkflowIntegration(t *testing.T) {
 	defer cancel()
 
 	// Create minimal orchestrator input
-	input := statemachine.OrchestratorInput{
+	input := workflow.OrchestratorInput{
 		RemoteURL:      "https://forgejo.riotpiao.com/rock/poimen",
 		TargetRepoPath: "/tmp/test-poimen-integration",
 		Milestone:      "T0",
-		Config: statemachine.OrchestratorConfig{
+		Config: workflow.OrchestratorConfig{
 			SystemPrompt: "You are a code generation assistant. Generate simple test code.",
-			RolePrompts: map[string]statemachine.PromptSpec{
+			RolePrompts: map[string]workflow.PromptSpec{
 				"planner": {
 					TemplateRef: "planner/default.tmpl",
-					Model: statemachine.ModelSpec{
+					Model: workflow.ModelSpec{
 						ModelID: "ornith",
 					},
 				},
 				"judge": {
 					TemplateRef: "judge/default.tmpl",
-					Model: statemachine.ModelSpec{
+					Model: workflow.ModelSpec{
 						ModelID: "ornith",
 					},
 				},
 				"implementer": {
 					TemplateRef: "implementer/default.tmpl",
-					Model: statemachine.ModelSpec{
+					Model: workflow.ModelSpec{
 						ModelID: "claude-sonnet-5",
 					},
 				},
@@ -170,7 +170,7 @@ func TestOrchestratorWorkflowIntegration(t *testing.T) {
 	runResp, err := c.ExecuteWorkflow(ctx, client.StartWorkflowOptions{
 		ID:        workflowID,
 		TaskQueue: "poimen-taskqueue",
-	}, statemachine.OrchestratorWorkflow, input)
+	}, workflow.OrchestratorWorkflow, input)
 
 	assert.NoError(t, err, "failed to execute orchestrator workflow")
 	t.Logf("✅ Orchestrator workflow started: %s", workflowID)