Qualify parameters in the LowLevelParticleFilters methods, add timeevol to FRD

[baggepinnen]

Summary

forward_trajectory(kf, d::AbstractIdData), smooth(kf, d) and smooth(kf, M, d) used parameters(kf) as the default value of p. LowLevelParticleFilters does not export parameters, so calls without p raised UndefVarError: parameters not defined in ControlSystemIdentification. The default is now LowLevelParticleFilters.parameters(kf).

smooth(kf::KalmanFilter, d) additionally required a change in LowLevelParticleFilters: its method smooth(kf::KalmanFilter, args...) was more specific than smooth(kf::AbstractFilter, d::AbstractIdData) and failed for AbstractIdData. LowLevelParticleFilters.jl#290 restricts that method to vector data (version 3.33.1). The new smooth test is therefore only run with LowLevelParticleFilters ≥ 3.33.1; the forward_trajectory test runs unconditionally. The compat bound is unchanged.

FRD and ControlSystemsBase 1.22

CI on this PR exposed an unrelated failure with ControlSystemsBase 1.22: nyquist(frd::FRD) calls freqresp(sys, w; balance). freqresp(::FRD, w) accepted no keyword arguments, so the call was dispatched to the generic freqresp(::LTISystem, w; balance), which failed with FieldError: type FRD has no field timeevol, and, once that was resolved, with a MethodError for numeric_type(::FRD).

• FRD now has the property timeevol, which returns Continuous(), consistent with its supertype LTISystem{Continuous}. iscontinuous(frd) therefore works. propertynames lists timeevol, nu and ny as well.
• freqresp(::FRD, w; kwargs...) accepts and ignores keyword arguments such as balance.

Other changes

• The absolute tolerance of the frequency-response comparison in test_basis_functions.jl is increased from 1e-10 to 2e-9. With ControlSystemsBase 1.22, the difference for the Kautz basis exceeded 1e-10 for about 70% of the random coefficient vectors (largest observed value 6.7e-10 over 300 draws; relative difference at most 2e-13).
• Version bump to 2.12.1.

Found during LowLevelParticleFilters.jl#288.

Tests

• test_subspace.jl checks forward_trajectory(kf, d) and smooth(kf, d) for a filter obtained from subspaceid.
• test_frd.jl checks iscontinuous(frd) and freqresp(frd, w; balance = false); it passes locally with ControlSystemsBase 1.22.0 (56 passed).
• test_subspace.jl passes locally on Julia 1.13 against the branch of LowLevelParticleFilters.jl#290 (2690 passed). The rest of the test suite was not run locally.

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Host: demeter2, Claude Code session a4b42284-297c-4d79-b33c-7149cef31ba8

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[codecov]

Codecov Report

❌ Patch coverage is 50.00000% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.50%. Comparing base (bfc0f7c) to head (6d49a13).

Files with missing lines	Patch %	Lines
src/subspace.jl	33.33%	2 Missing ⚠️
src/frd.jl	66.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #201      +/-   ##
==========================================
+ Coverage   89.49%   89.50%   +0.01%     
==========================================
  Files          15       15              
  Lines        2722     2726       +4     
==========================================
+ Hits         2436     2440       +4     
  Misses        286      286              

Flag	Coverage Δ
unittests	89.50% <50.00%> (+0.01%)	⬆️

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