1. 增加配置持久化

2. 完善细节

internal/config/config.go

@@ -0,0 +1,85 @@
+package config
+
+import (
+	"encoding/json"
+	"log"
+	"os"
+	"path/filepath"
+)
+
+// Config holds persistent application settings.
+type Config struct {
+	Theme          string `json:"theme"`
+	PreferredAccel string `json:"preferredAccel"`
+	OutputDir      string `json:"outputDir"`
+	NamingRule     string `json:"namingRule"`
+	FFmpegPath     string `json:"ffmpegPath"`
+	FFprobePath    string `json:"ffprobePath"`
+
+	dir string `json:"-"` // config directory path
+}
+
+var current *Config
+
+// Load reads config from AppData, creating defaults if needed.
+func Load() *Config {
+	dir := appDataDir()
+	_ = os.MkdirAll(dir, 0755)
+
+	cfg := &Config{
+		Theme:      "light",
+		NamingRule: "{name}_{codec}",
+		dir:        dir,
+	}
+
+	path := filepath.Join(dir, "config.json")
+	data, err := os.ReadFile(path)
+	if err != nil {
+		log.Printf("[config] read %s: %v (creating new)", path, err)
+		cfg.Save()
+		log.Printf("[config] created new config at %s", path)
+		return cfg
+	}
+
+	if err := json.Unmarshal(data, cfg); err != nil {
+		log.Printf("[config] corrupted config, resetting: %v", err)
+		cfg = &Config{Theme: "light", NamingRule: "{name}_{codec}", dir: dir}
+		cfg.Save()
+		return cfg
+	}
+
+	cfg.dir = dir
+	log.Printf("[config] loaded from %s: theme=%s accel=%s", path, cfg.Theme, cfg.PreferredAccel)
+	current = cfg
+	return cfg
+}
+
+// Save writes the current config to disk.
+func (c *Config) Save() {
+	path := filepath.Join(c.dir, "config.json")
+	data, err := json.MarshalIndent(c, "", "  ")
+	if err != nil {
+		log.Printf("[config] marshal error: %v", err)
+		return
+	}
+	if err := os.WriteFile(path, data, 0644); err != nil {
+		log.Printf("[config] write error: %v", err)
+		return
+	}
+	log.Printf("[config] saved: accel=%s out=%s", c.PreferredAccel, c.OutputDir)
+}
+
+// BinDir returns the directory where extracted ffmpeg binaries live.
+func (c *Config) BinDir() string {
+	d := filepath.Join(c.dir, "bin")
+	os.MkdirAll(d, 0755)
+	return d
+}
+
+// Get returns the current global config, loading if needed.
+func Get() *Config {
+	if current == nil {
+		return Load()
+	}
+	return current
+}