Fix isinplace detection for Basis types (#554)

Implement `DiffEqBase.isinplace` for `Basis` to correctly report whether
the basis supports in-place evaluation based on the `IMPL` type parameter.

The issue was that when creating an `ODEProblem` from a `Basis` with
controls but without implicit variables (Basis{false, true}), SciMLBase
would incorrectly detect it as in-place compatible. This caused a
MethodError because:

- Basis{false, CTRLS} only supports out-of-place signatures: (u, p, t) or (u, p, t, c)
- Basis{true, CTRLS} supports in-place signatures: (du, u, p, t) or (du, u, p, t, c)

The fix adds:
```julia
DiffEqBase.isinplace(::Basis{IMPL, CTRLS}, n) where {IMPL, CTRLS} = IMPL
```

This ensures that `isinplace` returns `true` only when the basis has
implicit variables (IMPL=true) and supports in-place evaluation,
and `false` otherwise.

Fixes #554

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

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

Author: ChrisRackauckas

src/basis/type.jl

@@ -605,3 +605,8 @@ end
 function Base.show(io::IO, ::MIME"text/plain", b::AbstractBasis)
     Base.print(io, b)
 end
+
+# SciMLBase interface - declare whether this is an in-place function
+# IMPL=true means the basis has implicit variables and supports in-place evaluation
+# IMPL=false means the basis is out-of-place only
+DiffEqBase.isinplace(::Basis{IMPL, CTRLS}, n) where {IMPL, CTRLS} = IMPL