ax(database): replace prose comment on Initialize with usage example

AX Principle 2: comments must show concrete usage, not restate the
function name. "Initialize opens the database connection and creates
tables" restated the signature — replaced with a callable example.

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

pkg/database/database.go

@@ -47,7 +47,8 @@ func defaultDBPath() (string, error) {
 	return filepath.Join(dataDir, "mining.db"), nil
 }
 
-// Initialize opens the database connection and creates tables
+// Initialize opens the SQLite database and creates all required tables.
+// database.Initialize(database.Config{Enabled: true, Path: "/data/mining.db", RetentionDays: 30})
 func Initialize(cfg Config) error {
 	databaseMutex.Lock()
 	defer databaseMutex.Unlock()