fix(laravel): bind named relation constraint arguments

[shuvroroy]

Relation callback inference assumed the first supplied argument named the relationship. Calls such as Team::has(callback: ..., relation: 'stocks.warehouse') therefore lost the related model and custom builder. Bind the relation and callback against the installed method declaration using the shared argument binder, and apply the override only to the actual constraint argument.

Adds regression coverage for reordered arguments, omitted defaults, static/instance/null-safe calls, block/arrow callbacks, the whereRelation column callback, and a closure in an unrelated parameter. Includes a Laravel demo and runtime assertion; removes completed L57 from the backlog.

Stack: depends on #449 (L56), above #448 and #447. This stacked PR targets upstream main, so its diff includes the unmerged dependencies. The final commit contains L57; merge the dependencies first.

Validation: full cargo test, both required clippy runs, cargo fmt --check, PHP syntax/runtime assertions, and Laravel analysis with exactly its three intentional diagnostics.

[codecov-commenter]

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Codecov Report

❌ Patch coverage is 95.32164% with 8 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/type_engine/variable/closure_resolution.rs	89.36%	5 Missing ⚠️
...engine/variable/forward_walk/callable_inference.rs	96.49%	2 Missing ⚠️
src/virtual_members/laravel/builder.rs	98.38%	1 Missing ⚠️

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