Fix formatting nits in Lattice.lean and Unit.lean

- Spa/Lattice.lean: add the missing space in the PointedLTSeries binder list
  ((f t : α) (n : ℕ)).
- Spa/Lattice/Unit.lean: use rfl instead of refl _, and split the ~200-column
  longestChain record literal across lines, one field per line.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

lean/Spa/Lattice.lean

@@ -50,7 +50,7 @@ end Folds
 def BoundedChains (α : Type*) [Preorder α] (n : ℕ) : Prop :=
   ∀ c : LTSeries α, c.length ≤ n
 
-structure PointedLTSeries (α : Type*) (f t : α)(n : ℕ) [Preorder α] where
+structure PointedLTSeries (α : Type*) (f t : α) (n : ℕ) [Preorder α] where
   series : LTSeries α
   head_series : series.head = f
   last_series : series.last = t