Fix integer bounds error in OptimizationMOI

Fixes #528 - Added Float64 conversion for bounds in MOI.GreaterThan and
MOI.LessThan constraints to handle integer constraint vectors properly.

Previously, passing integer vectors for lb/ub parameters would cause:
```
MathOptInterface.UnsupportedConstraint{MathOptInterface.VariableIndex,
MathOptInterface.GreaterThan{Int64}}
```

Now integer bounds are automatically converted to Float64, matching the
behavior in moi.jl and preventing confusing errors.

Changes:
- Convert evaluator.lb[i] to Float64 in MOI.GreaterThan constraint
- Convert evaluator.ub[i] to Float64 in MOI.LessThan constraint

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: ChrisRackauckas

lib/OptimizationMOI/src/nlp.jl

@@ -490,10 +490,10 @@ function _add_moi_variables!(opt_setup, evaluator::MOIOptimizationNLPEvaluator)
 
     for i in 1:num_variables
         if evaluator.lb !== nothing && evaluator.lb[i] > -Inf
-            MOI.add_constraint(opt_setup, θ[i], MOI.GreaterThan(evaluator.lb[i]))
+            MOI.add_constraint(opt_setup, θ[i], MOI.GreaterThan(Float64(evaluator.lb[i])))
         end
         if evaluator.ub !== nothing && evaluator.ub[i] < Inf
-            MOI.add_constraint(opt_setup, θ[i], MOI.LessThan(evaluator.ub[i]))
+            MOI.add_constraint(opt_setup, θ[i], MOI.LessThan(Float64(evaluator.ub[i])))
         end
         if evaluator.int !== nothing && evaluator.int[i]
             if evaluator.lb !== nothing && evaluator.lb[i] == 0 &&