Bring wine and shallot to a boil in a small saucepan over high heat. Reduce heat to low; add salmon. Gently poach until salmon is barely opaque in center, about 5 minutes. Using a slotted spoon, transfer to a paper towel-lined plate to drain. Strain poaching liquid through a fine-mesh sieve; set aside shallot and discard liquid. Place salmon and shallot in a large bowl; cover and chill until completely cooled.

Add smoked salmon, 1/2 cup mayonnaise, chives, and 1 Tbsp. lemon juice to salmon and shallot. Gently mix just to combine (salmon will break up a little, but do not overmix or a paste will form). Season to taste with salt, pepper, and more mayonnaise and lemon juice, if desired. DO AHEAD: Rillettes can be made 1 day ahead. Cover and chill.

Serve rillettes cold with toasted slices of baguette.