Fix undefined default_linear_interpolation error in OrdinaryDiffEqSymplecticRK

- Add default_linear_interpolation to the imports in OrdinaryDiffEqSymplecticRK.jl
- Use imported function directly instead of OrdinaryDiffEqCore.default_linear_interpolation

This fixes the precompilation error where default_linear_interpolation was
called but not imported, causing UndefVarError during package loading.

Fixes #2611

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

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

Author: ChrisRackauckas

lib/OrdinaryDiffEqSymplecticRK/src/OrdinaryDiffEqSymplecticRK.jl

@@ -12,7 +12,7 @@ import OrdinaryDiffEqCore: alg_order, calculate_residuals!,
                            constvalue, _unwrap_val,
                            explicit_rk_docstring, trivial_limiter!,
                            _ode_interpolant!, _ode_addsteps!, get_fsalfirstlast,
-                           generic_solver_docstring
+                           generic_solver_docstring, default_linear_interpolation
 using FastBroadcast, Polyester, MuladdMacro, RecursiveArrayTools
 import OrdinaryDiffEqCore
 

lib/OrdinaryDiffEqSymplecticRK/src/algorithms.jl

@@ -44,7 +44,7 @@ monaghan2005 = """
     monaghan2005, "", "")
 struct VerletLeapfrog <: OrdinaryDiffEqPartitionedAlgorithm end
 
-OrdinaryDiffEqCore.default_linear_interpolation(alg::VerletLeapfrog, prob) = true
+default_linear_interpolation(alg::VerletLeapfrog, prob) = true
 
 @doc generic_solver_docstring(
     "2nd order explicit symplectic integrator. Drift-kick-drift form of `VerletLeapfrog`
@@ -54,7 +54,7 @@ designed to work when `f1` depends on `v`. Requires two evaluation of `f1` per s
     monaghan2005, "", "")
 struct LeapfrogDriftKickDrift <: OrdinaryDiffEqPartitionedAlgorithm end
 
-OrdinaryDiffEqCore.default_linear_interpolation(alg::LeapfrogDriftKickDrift, prob) = true
+default_linear_interpolation(alg::LeapfrogDriftKickDrift, prob) = true
 
 @doc generic_solver_docstring("2nd order explicit symplectic integrator.",
     "PseudoVerletLeapfrog",