fix(cmd): add missing defer db.Close(), fix uncheked errors

[vomar3]

Fixed #73

[vomar3]

I noticed that error checking isn't implemented everywhere for example, here

cmd/restore.go:

Run: func(cmd *cobra.Command, args []string) {
		os.MkdirAll(".eko/snapshots", 0755)
		database := db.InitDB()
		defer database.Close()
		database.Exec(`
			CREATE TABLE IF NOT EXISTS snapshots (
				id TEXT PRIMARY KEY,
				message TEXT,
				path TEXT,
				created_at DATETIME DEFAULT CURRENT_TIMESTAMP
			)
		`)
		fmt.Println("Eko initialized.")

		// Check if a .git directory exists
		if info, err := os.Stat(".git"); err == nil && info.IsDir() {
			fmt.Println("Tip: A Git repository was detected. Eko runs independently of Git but automatically ignores the .git directory.")
		}
	},

So, I can replace Run with RunE and return an error here and in other places in the code.