Initialize blog scaffold

Add the CLI, site, and sample content so the project can run locally.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend/internal/cli/storage_test.go

@@ -0,0 +1,68 @@
+package cli
+
+import (
+	"path/filepath"
+	"testing"
+)
+
+func TestSQLitePostImportLoadExport(t *testing.T) {
+	root := t.TempDir()
+	db, err := openSQLite(filepath.Join(root, ".osaet.db"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	if err := applySQLiteSchema(db); err != nil {
+		t.Fatal(err)
+	}
+
+	publishedAt := "2026-05-28T12:00:00+08:00"
+	post := postFile{
+		Path: filepath.Join(root, defaultPostsDir, "hello.md"),
+		Frontmatter: postFrontmatter{
+			ID:          "post-1",
+			Slug:        "hello",
+			Title:       "Hello",
+			Status:      "published",
+			Tags:        []string{"go"},
+			Version:     1,
+			SlugSource:  "manual",
+			PublishedAt: &publishedAt,
+			CreatedAt:   "2026-05-28T11:00:00+08:00",
+			UpdatedAt:   "2026-05-28T12:00:00+08:00",
+		},
+		Body: "Body\n",
+	}
+
+	if err := upsertSQLitePost(root, db, post); err != nil {
+		t.Fatal(err)
+	}
+
+	posts, err := loadSQLitePosts(db)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(posts) != 1 {
+		t.Fatalf("loaded %d posts, want 1", len(posts))
+	}
+	if posts[0].Frontmatter.Slug != "hello" || posts[0].Body != "Body\n" {
+		t.Fatalf("loaded post mismatch: %#v", posts[0])
+	}
+
+	exported, skipped, err := exportPostsToFilesCount(root, posts, false)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if exported != 1 || skipped != 0 {
+		t.Fatalf("exported=%d skipped=%d", exported, skipped)
+	}
+
+	read, err := readPostFile(filepath.Join(root, defaultPostsDir, "hello.md"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if read.Frontmatter.Title != "Hello" {
+		t.Fatalf("exported title = %q", read.Frontmatter.Title)
+	}
+}