Derive the hand-written overrides from the generator

[ViralBShah]

Motivation

The three files under src/overrides/ existed only to paper over gaps in the wrapper generator. Since OpenCV.jl already owns its fork of the Julia-specific generator (the upstream opencv_contrib copy is effectively unmaintained), the lower-risk home for this logic is the generator itself. Each gap is now closed there, the overrides are deleted, and their behaviour is produced by julia gen/regenerate.jl.

Net: −156 / +54 lines of hand-maintained code; src/overrides/ is gone.

Changes

Covariance — deletes covariance.jl (62 lines).
gen3_julia_cxx.py emits the covariant AbstractVector{<:InputArray} for vector-of-array parameters instead of the invariant Array{InputArray, 1}, so a natural Vector{Array{Float32,3}} dispatches without an OpenCV.InputArray[…] cast. Applied to the type annotation only; default-value lookups still key off the unrelaxed type. (issues #18, #60)

Defaults — deletes defaults.jl (22 lines).
Six defval.txt entries let the generator emit the keyword-default overloads for ORB_create and SimpleBlobDetector_create. The diff is surgical — only those two overloads appear.

GUI / Cascade callbacks — moved out of convenience.jl.
Relocated to gen/binding_templates_jl/manual_cxx.jl, emitted verbatim into cv_cxx_wrap.jl as a "Manual Wrapping" section — the Julia counterpart of the existing C++ block in cv_core.cpp. No C++/JLL change (those symbols are already compiled); behaviour preserved exactly.

VideoWriter_fourcc string form — moved to the hand-written src/videoio.jl (not an override).

⚠️ Behaviour change to note

ORB_create()'s default scoreType is now the OpenCV-faithful ORB_HARRIS_SCORE. The deleted override hard-coded ORB_FAST_SCORE, which was a bug — but this does change descriptor behaviour for callers who relied on the implicit default.

Caveat

The GUI callbacks (createButton / setMouseCallback / createTrackbar) reference jl_cpp_cv2, which is defined nowhere and untested — they would UndefVarError if called. They are relocated with exact parity; fixing/removing them is left to separate work, since the highgui C++ side can't be rebuilt/tested here.

Verification

• julia gen/regenerate.jl is byte-for-byte idempotent → the CI git diff --exit-code guard stays green.
• Full test suite: 310/310 pass.
• The #60 calibrate* hasmethod tests are updated to the generated keyword-form arity (they previously asserted the override's args... reduced-arity shape), preserving their concrete-element-dispatch intent. Stale src/overrides/ / src/patches*.jl references in README.md and test_imgproc.jl are corrected.

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.45%. Comparing base (30e41b7) to head (43565d3).

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #96      +/-   ##
==========================================
+ Coverage   84.67%   91.45%   +6.78%     
==========================================
  Files          13       11       -2     
  Lines         274      234      -40     
==========================================
- Hits          232      214      -18     
+ Misses         42       20      -22     

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.