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/config.go

@@ -0,0 +1,117 @@
+package cli
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"gopkg.in/yaml.v3"
+)
+
+func runConfig(root string, args []string) error {
+	if len(args) == 0 {
+		return errors.New("missing config subcommand")
+	}
+	switch args[0] {
+	case "import":
+		return runConfigImport(root, args[1:])
+	case "export":
+		return runConfigExport(root, args[1:])
+	case "diff":
+		return runConfigDiff(root, args[1:])
+	case "sync":
+		return runConfigSync(root, args[1:])
+	default:
+		return fmt.Errorf("unknown config subcommand %q", args[0])
+	}
+}
+
+func loadLocalConfig(root string) (localConfig, error) {
+	var config localConfig
+	path := filepath.Join(root, "config/local.yaml")
+	data, err := os.ReadFile(path)
+	if err != nil {
+		if errors.Is(err, os.ErrNotExist) {
+			return config, nil
+		}
+		return config, err
+	}
+	if err := yaml.Unmarshal(data, &config); err != nil {
+		return config, fmt.Errorf("%s: %w", path, err)
+	}
+	return config, nil
+}
+
+func readSiteConfig(root string) (siteConfigFile, error) {
+	var config siteConfigFile
+	path := filepath.Join(root, "config/site.yaml")
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return config, err
+	}
+	if err := yaml.Unmarshal(data, &config); err != nil {
+		return config, fmt.Errorf("%s: %w", path, err)
+	}
+	return config, nil
+}
+
+func writeSiteConfig(root string, config siteConfigFile) error {
+	var out bytes.Buffer
+	encoder := yaml.NewEncoder(&out)
+	encoder.SetIndent(2)
+	if err := encoder.Encode(config); err != nil {
+		return err
+	}
+	if err := encoder.Close(); err != nil {
+		return err
+	}
+
+	path := filepath.Join(root, "config/site.yaml")
+	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
+		return err
+	}
+	tmp := path + ".tmp"
+	if err := os.WriteFile(tmp, out.Bytes(), 0o644); err != nil {
+		return err
+	}
+	return os.Rename(tmp, path)
+}
+
+func defaultSiteConfig() string {
+	return `meta:
+  config_version: 1
+  updated_at: "2026-05-28T12:00:00+08:00"
+  updated_by: "cli"
+
+site:
+  title: "Osaet"
+  description: "Personal blog"
+  base_url: "http://localhost:4321"
+  language: "zh-CN"
+  timezone: "Asia/Shanghai"
+
+content:
+  posts_dir: "content/posts"
+  assets_dir: "content/assets"
+
+build:
+  astro_project: "frontend/site"
+  output_dir: "dist/site"
+`
+}
+
+func defaultLocalExampleConfig() string {
+	return `database:
+  driver: "sqlite"
+  sqlite_path: ".osaet/osaet.db"
+  postgres_dsn: ""
+
+deepseek:
+  api_key: ""
+  api_key_env: "DEEPSEEK_API_KEY"
+  base_url: "https://api.deepseek.com"
+  model: "deepseek-v4-pro"
+`
+}