feat: add admin publishing workflow and yar theme

Add Go/Postgres admin APIs, Angular admin UI, manual build flow, asset uploads, markdown import/export, configurable slug generation, and the Yar reading theme. Exclude local docs and generated development artifacts from version control.

backend/internal/postimport/import_test.go

@@ -0,0 +1,125 @@
+package postimport
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func TestNormalizeLegacyTime(t *testing.T) {
+	got, err := normalizeLegacyTime("2026-01-13 01:25:27.486491+00")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got != "2026-01-13T01:25:27Z" {
+		t.Fatalf("normalized time = %q", got)
+	}
+}
+
+func TestArticleToPostFallbackSlugAndBody(t *testing.T) {
+	root := t.TempDir()
+	postsDir := filepath.Join(root, defaultPostsDir)
+	if err := os.MkdirAll(postsDir, 0o755); err != nil {
+		t.Fatal(err)
+	}
+
+	post, skipped, err := articleToPost(root, postsDir, csvArticle{
+		Title:       "Hello World",
+		BodyMD:      "\nBody\n",
+		Status:      "published",
+		CreatedAt:   "2026-01-13 01:25:27.486491+00",
+		UpdatedAt:   "2026-01-13 01:25:27.486491+00",
+		PublishedAt: "2026-01-13 01:25:27.486491+00",
+		Type:        "post",
+	}, false)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if skipped {
+		t.Fatal("expected importable post")
+	}
+	if post.Frontmatter.Slug != "hello-world" {
+		t.Fatalf("slug = %q", post.Frontmatter.Slug)
+	}
+	if post.Body != "Body\n" {
+		t.Fatalf("body = %q", post.Body)
+	}
+	if post.Frontmatter.PublishedAt == nil || *post.Frontmatter.PublishedAt != "2026-01-13T01:25:27Z" {
+		t.Fatalf("published_at = %#v", post.Frontmatter.PublishedAt)
+	}
+}
+
+func TestArticleToPostSkipsExistingWithoutOverwrite(t *testing.T) {
+	root := t.TempDir()
+	postsDir := filepath.Join(root, defaultPostsDir)
+	if err := os.MkdirAll(postsDir, 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(postsDir, "smoking.md"), []byte("existing"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	_, skipped, err := articleToPost(root, postsDir, csvArticle{
+		Slug:      "smoking",
+		Title:     "抽烟",
+		BodyMD:    "Body",
+		Status:    "published",
+		CreatedAt: "2026-01-13 01:25:27.486491+00",
+		UpdatedAt: "2026-01-13 01:25:27.486491+00",
+		Type:      "post",
+	}, false)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !skipped {
+		t.Fatal("expected existing file to be skipped")
+	}
+}
+
+func TestImportWritesMarkdown(t *testing.T) {
+	root := t.TempDir()
+	if err := os.MkdirAll(filepath.Join(root, "backend", "cmd", "osaetctl"), 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.MkdirAll(filepath.Join(root, "frontend", "site"), 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(root, "frontend", "site", "package.json"), []byte("{}"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	csvPath := filepath.Join(root, "articles.csv")
+	csvContent := strings.Join([]string{
+		"id,slug,title,body_md,body_html,status,archive_id,author_id,published_at,created_at,updated_at,type",
+		"post-1,test-post,Test Post,\"Line 1\n\nLine 2\",,published,,,2026-01-13 01:25:27.486491+00,2026-01-13 01:25:27.486491+00,2026-01-13 01:25:27.486491+00,post",
+	}, "\n")
+	if err := os.WriteFile(csvPath, []byte(csvContent), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	result, err := Import(Options{CSVPath: csvPath, PostsDir: defaultPostsDir, WorkingDir: root})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if result.Imported != 1 || result.SkippedExisting != 0 || result.SkippedNonPost != 0 {
+		t.Fatalf("result = %#v", result)
+	}
+
+	data, err := os.ReadFile(filepath.Join(root, defaultPostsDir, "test-post.md"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	content := string(data)
+	for _, want := range []string{
+		"slug: test-post",
+		"title: Test Post",
+		"status: published",
+		"published_at: \"2026-01-13T01:25:27Z\"",
+		"Line 1",
+		"Line 2",
+	} {
+		if !strings.Contains(content, want) {
+			t.Fatalf("expected output to contain %q\n%s", want, content)
+		}
+	}
+}