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/integration.go

@@ -0,0 +1,43 @@
+package activity
+
+import (
+	"context"
+	"os/exec"
+)
+
+// RunIntegrationTestInput is input to RunIntegrationTestActivity.
+type RunIntegrationTestInput struct {
+	WorktreePath string
+	TestCmd      string
+}
+
+// RunIntegrationTestOutput is the output of RunIntegrationTestActivity.
+type RunIntegrationTestOutput struct {
+	Passed bool
+	Logs   string
+}
+
+// RunIntegrationTestActivity runs integration tests in the worktree.
+func RunIntegrationTestActivity(ctx context.Context, in RunIntegrationTestInput) (RunIntegrationTestOutput, error) {
+	if in.TestCmd == "" {
+		// No test command, assume pass
+		return RunIntegrationTestOutput{Passed: true, Logs: "No test command provided"}, nil
+	}
+
+	// Run test command
+	cmd := exec.CommandContext(ctx, "sh", "-c", in.TestCmd)
+	cmd.Dir = in.WorktreePath
+
+	output, err := cmd.CombinedOutput()
+	if err != nil {
+		return RunIntegrationTestOutput{
+			Passed: false,
+			Logs:   string(output) + "\nError: " + err.Error(),
+		}, nil
+	}
+
+	return RunIntegrationTestOutput{
+		Passed: true,
+		Logs:   string(output),
+	}, nil
+}