Migration: implement parameter contract method for all strategies (CTBase v0.28.0-beta)

[ocots]

Context

CTBase v0.28.0-beta introduces a breaking change in the strategy parameter contract. See control-toolbox/CTBase.jl#497 for the full PR.

What changed in CTBase

• get_parameter_type is removed from the public API.
• A new parameter(::Type{<:S}) contract method is added to AbstractStrategy. Every concrete strategy must implement it:
  • Non-parameterized: Strategies.parameter(::Type{<:MyStrategy}) = nothing
  • Parameterized: Strategies.parameter(::Type{<:MyStrategy{P}}) where {P<:Strategies.AbstractStrategyParameter} = P
  • The default stub throws Exceptions.NotImplemented so any strategy that forgets to implement it fails loudly at load time.
• _default_parameter is renamed to default_parameter (now exported).
• parameter and default_parameter are now exported from CTBase.Strategies.

Migration steps

1. For each concrete strategy struct in CTSolvers, add a parameter method:

   # Non-parameterized strategy
   CTBase.Strategies.parameter(::Type{<:Ipopt}) = nothing
   
   # Parameterized strategy
   CTBase.Strategies.parameter(::Type{<:MadNLP{P}}) where {P<:CTBase.Strategies.AbstractStrategyParameter} = P

2. Rename all _default_parameter calls to default_parameter:

   # Before
   CTBase.Strategies._default_parameter(::Type{<:MadNLP}) = CTBase.Strategies.CPU
   
   # After
   CTBase.Strategies.default_parameter(::Type{<:MadNLP}) = CTBase.Strategies.CPU

3. Remove any usage of get_parameter_type — replace with parameter.

4. Run tests against CTBase feature/parameter-contract branch (or main after merge).