Implement matrix and vector interfaces

[goerz]

This properly defines supports_vector_interface and supports_matrix_interface for GradVector and GradgenOperator, respectively, and implement the full required interface, as checked by check_operator and check_state.

This is a prerequisite to propagating gradient vectors via ExponentialUtilities (or similar external packages that assume an AbstractVector interface), see JuliaQuantumControl/QuantumPropagators.jl#97

[codecov]

Codecov Report

❌ Patch coverage is 96.26168% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 87.5%. Comparing base (856448a) to head (db43eca).
⚠️ Report is 3 commits behind head on master.

Files with missing lines	Patch %	Lines
src/linalg.jl	96.1%	4 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##           master     #18     +/-   ##
========================================
+ Coverage    80.0%   87.5%   +7.5%     
========================================
  Files           5       5             
  Lines         185     278     +93     
========================================
+ Hits          148     243     +95     
+ Misses         37      35      -2     

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[Copilot]

Pull request overview

This PR expands GradVector and GradgenOperator to provide the vector/matrix interfaces expected by QuantumPropagators.Interfaces (via check_state / check_operator), enabling compatibility with external propagation utilities that assume array-like behavior.

Changes:

• Adds full vector-like Base/LinearAlgebra interface methods for GradVector (e.g., size, getindex, setindex!, iterate, and similar variants).
• Adds matrix-like Base/LinearAlgebra interface methods for GradgenOperator (e.g., getindex, iterate, length, and similar variants) and defines supports_matrix_interface.
• Extends interface-focused tests to validate the new behaviors and trait reporting.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 5 comments.

File	Description
src/linalg.jl	Implements vector/matrix interface methods (size/getindex/iterate/similar etc.) plus mul! and dot overloads to satisfy interface checks.
src/grad_vector.jl	Defines supports_vector_interface / type-based supports_inplace for GradVector and updates resetgradvec! to use type-based trait checks.
src/gradgen_operator.jl	Defines type-based supports_inplace and supports_matrix_interface for GradgenOperator.
test/test_interface.jl	Adds targeted tests for vector/matrix interface compliance and trait behavior for both dense and static backends.

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[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated no new comments.

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