Remove unused cached var in config package

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

internal/config/config.go

@@ -53,10 +53,7 @@ var defaults = Config{
 	LastEventID:            0,
 }
 
-var (
-	mu       sync.Mutex
-	cached   *Config
-)
+var mu sync.Mutex
 
 // Load reads config from disk, merging with defaults.
 func Load() Config {
@@ -71,7 +68,7 @@ func Load() Config {
 	if err := json.Unmarshal(data, &cfg); err != nil {
 		log.Printf("config: parse error: %v", err)
 	}
-	cached = &cfg
+
 	return cfg
 }
 
@@ -88,7 +85,7 @@ func Save(cfg Config) error {
 	if err != nil {
 		return err
 	}
-	cached = &cfg
+
 	return os.WriteFile(ConfigPath(), data, 0o644)
 }