Avoid JSONReadStyle trait ambiguity

[quinnj]

Summary

• avoid wrapping custom JSONStyles in JSONReadStyle on the default parse path
• make JSON lazy-value lifting available on JSONStyle itself, with exact JSONReadStyle bridge methods
• add issue Method ambiguity for custom types with generically defined StructUtils.StructStyle methods #464 regression coverage for broad StructStyle and broad JSONStyle dictlike definitions

Root Cause

JSONReadStyle forwarding introduced a dispatch crossing between JSON wrapper-style methods and user methods that are broad on the style axis but specific on the target type, such as dictlike(::StructStyle, ::Type{A}).

Testing

• git diff --check
• julia --project=/tmp/jsonjl-464-slim --startup-file=no -e 'using Pkg; Pkg.instantiate(); Pkg.test(; coverage=false)'

Fixes #464

Co-authored by Codex

[codecov]

Codecov Report

❌ Patch coverage is 94.73684% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 90.39%. Comparing base (6e487a9) to head (3a8782a).

Files with missing lines	Patch %	Lines
src/parse.jl	94.73%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #465      +/-   ##
==========================================
+ Coverage   90.32%   90.39%   +0.07%     
==========================================
  Files           7        7              
  Lines        1416     1427      +11     
==========================================
+ Hits         1279     1290      +11     
  Misses        137      137              

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