ax(mining): replace prose comments with usage examples on LoadMinersConfig/SaveMinersConfig

AX Principle 2: comments as usage examples. Both functions had prose descriptions
that restated the signature ("loads the miners configuration from the file system").
Replace with concrete call-site examples that show how to use the return value.

Co-Authored-By: Charon <charon@lethean.io>

pkg/mining/config_manager.go

@@ -47,7 +47,9 @@ func getMinersConfigPath() (string, error) {
 	return xdg.ConfigFile("lethean-desktop/miners/config.json")
 }
 
-// LoadMinersConfig loads the miners configuration from the file system.
+// cfg, err := LoadMinersConfig()
+// if err != nil { return err }
+// cfg.Database.Enabled = false
 func LoadMinersConfig() (*MinersConfig, error) {
 	configMu.RLock()
 	defer configMu.RUnlock()
@@ -82,8 +84,8 @@ func LoadMinersConfig() (*MinersConfig, error) {
 	return &configuration, nil
 }
 
-// SaveMinersConfig saves the miners configuration to the file system.
-// Uses atomic write pattern: write to temp file, then rename.
+// cfg.Database.RetentionDays = 60
+// if err := SaveMinersConfig(cfg); err != nil { return err }
 func SaveMinersConfig(configuration *MinersConfig) error {
 	configMu.Lock()
 	defer configMu.Unlock()