Resample dynamic outputs without a solver implementation

[sylvesterkaczmarek]

Fixes #78.

Evaluate resampled dynamic outputs through the model's existing output equations, already used by point_analysis, instead of requiring the retained solver implementation. File-loaded and detached results retain their scalar/vector outputs, time and parameter dependence, and modal behavior. No solver is rebuilt; time grids, interpolation and event handling are unchanged.

Validation

macOS arm64, Python 3.12.11:

• Full suite: 95 passed, 2 pre-existing skips, with the same 40 warnings as unchanged main (86 passed, 2 skipped).
• Nine new cases cover deleted/None implementations, save/load round trips, event inclusion, time/parameter-dependent and modal outputs, chained resampling, disabled outputs, and models without outputs. Eight cases failed against unchanged main.
• Existing trajectory tests, Ruff lint/format checks, and git diff --check passed.

The separate coincident-event resampling issue #77 and solver changes in #93 are outside this PR. Other platforms and CVODE were not tested.