Initial commit: email-openclaw bridge v1

Full pipeline: IMAP ingress -> OpenClaw dispatch -> callback -> SMTP reply.
SQLite stateful storage with idempotency, threading, and retry logic.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

internal/database/testhelper.go

@@ -0,0 +1,35 @@
+package database
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"gorm.io/gorm"
+)
+
+// TestDB holds a test database instance with automatic cleanup.
+type TestDB struct {
+	DB      *gorm.DB
+	cleanup func()
+}
+
+// NewTestDB creates a temporary SQLite database for testing.
+func NewTestDB(t *testing.T) *TestDB {
+	t.Helper()
+
+	dir := t.TempDir()
+	dbPath := filepath.Join(dir, "test.db")
+
+	db, err := Open(dbPath)
+	if err != nil {
+		t.Fatalf("open test db: %v", err)
+	}
+
+	return &TestDB{
+		DB: db,
+		cleanup: func() {
+			os.RemoveAll(dir)
+		},
+	}
+}