feat(app): implement basic function

General
- 配置界面支持配置对象存储桶
- 快捷键进入截图
- 一键上传截图 & 复制截图链接

MacOS
- 状态栏指示器和应用图标

internal/infrastructure/config/file_store.go

@@ -0,0 +1,89 @@
+// Package config provides JSON-file backed persistence for AppConfig.
+//
+// Design rationale:
+// - JSON keeps the file human-readable, which is useful while the MVP has
+//   no settings UI for every option.
+// - Storage location follows os.UserConfigDir() so each platform places it
+//   in the canonical spot (macOS: ~/Library/Application Support/SnapGo).
+// - File mode 0600 / dir mode 0700 mitigate accidental leakage of access
+//   keys before we wire up the OS keychain (deferred to a later spec).
+package config
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"sync"
+
+	"github.com/mmmy/snapgo/internal/domain"
+)
+
+// FileStore implements load/save of AppConfig on the local filesystem.
+//
+// All methods are safe for concurrent use.
+type FileStore struct {
+	mu   sync.RWMutex
+	path string
+}
+
+// NewFileStore resolves the on-disk path and creates the parent directory
+// with permissions 0700 if missing.
+func NewFileStore() (*FileStore, error) {
+	dir, err := os.UserConfigDir()
+	if err != nil {
+		return nil, fmt.Errorf("resolve user config dir: %w", err)
+	}
+	appDir := filepath.Join(dir, "SnapGo")
+	if err := os.MkdirAll(appDir, 0o700); err != nil {
+		return nil, fmt.Errorf("ensure config dir: %w", err)
+	}
+	return &FileStore{path: filepath.Join(appDir, "config.json")}, nil
+}
+
+// Path exposes the absolute config file path (mainly for diagnostics / UI).
+func (s *FileStore) Path() string {
+	return s.path
+}
+
+// Load reads the config file. If the file does not exist OR cannot be parsed,
+// the default config is returned with a non-nil error so the caller can decide
+// whether to surface the parse failure to the user.
+func (s *FileStore) Load() (domain.AppConfig, error) {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+
+	cfg := domain.DefaultAppConfig()
+	data, err := os.ReadFile(s.path)
+	if err != nil {
+		if errors.Is(err, os.ErrNotExist) {
+			return cfg, nil
+		}
+		return cfg, fmt.Errorf("read config: %w", err)
+	}
+	if err := json.Unmarshal(data, &cfg); err != nil {
+		return domain.DefaultAppConfig(), fmt.Errorf("parse config: %w", err)
+	}
+	return cfg, nil
+}
+
+// Save persists the supplied config atomically (write-temp + rename) so
+// crashes mid-write cannot leave a half-written file.
+func (s *FileStore) Save(cfg domain.AppConfig) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	data, err := json.MarshalIndent(cfg, "", "  ")
+	if err != nil {
+		return fmt.Errorf("marshal config: %w", err)
+	}
+	tmp := s.path + ".tmp"
+	if err := os.WriteFile(tmp, data, 0o600); err != nil {
+		return fmt.Errorf("write tmp config: %w", err)
+	}
+	if err := os.Rename(tmp, s.path); err != nil {
+		return fmt.Errorf("commit config: %w", err)
+	}
+	return nil
+}