Add SPH correction consistency study

[svchb]

Summary

• document consistency degrees separately from full-discretization convergence orders
• add a manufactured study for interpolation, density, gradient, and pressure operators
• report truncated-boundary and symmetric-interior behavior separately
• cover every supported correction and pressure pairing
• write reproducible Markdown and CSV output
• keep reduced-resolution regression assertions in a dedicated validation test file

Stack

Depends on #1285. This PR targets main and temporarily includes the complete preceding stack.

Review-only diff: svchb/TrixiParticles.jlOpen@feature/independent-correction-configuration...validation/correction-consistency-study

Isolated layer: 5 files, 780 additions.

Verification

• julia --project=. validation/corrections/convergence.jl passed
• complete unit suite passed
• JuliaFormatter and git diff --check passed

[codecov]

Codecov Report

❌ Patch coverage is 92.81314% with 35 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.64%. Comparing base (a720b1d) to head (3fb26bb).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
test/examples/gpu.jl	0.00%	23 Missing ⚠️
src/general/corrections.jl	89.28%	6 Missing ⚠️
src/io/io.jl	0.00%	5 Missing ⚠️
src/schemes/structure/rigid_body/system.jl	93.33%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1286      +/-   ##
==========================================
+ Coverage   90.39%   90.64%   +0.25%     
==========================================
  Files         138      147       +9     
  Lines       11322    11772     +450     
==========================================
+ Hits        10234    10671     +437     
- Misses       1088     1101      +13     

Flag	Coverage Δ
total	90.65% <92.81%> (+0.25%)	⬆️
unit	79.40% <92.81%> (+1.91%)	⬆️

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