Add vortex street example file

[efaulhaber]

Ported from #781.

[Copilot]

Pull request overview

This PR adds a new 2D “vortex street” fluid example (flow past a circular cylinder, based on Tafuni et al. 2018) and wires it into the examples test suite to ensure it runs successfully and without RHS allocations.

Changes:

• Add examples/fluid/vortex_street_2d.jl defining the vortex street simulation setup (fluid system, open boundaries, wall/cylinder boundaries, callbacks, solve).
• Add a corresponding @trixi_testset in test/examples/examples_fluid.jl to execute the example for a short tspan and validate success + zero RHS allocations.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
test/examples/examples_fluid.jl	Adds a test entry to run the new vortex street example and assert success/no allocations.
examples/fluid/vortex_street_2d.jl	Introduces the full vortex-street simulation configuration with open boundaries and cylinder obstacle.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.04%. Comparing base (f883a8a) to head (08e758d).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1221   +/-   ##
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  Coverage   90.04%   90.04%           
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  Files         136      136           
  Lines       10596    10596           
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  Hits         9541     9541           
  Misses       1055     1055           

Flag	Coverage Δ
total	90.05% <ø> (ø)
unit	70.77% <ø> (ø)

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[svchb]

move down to where it is used

[efaulhaber]

This is the "Experiment Setup" section. We always define values like flow direction and Reynolds number there.