fix(lazyvalue): OwnedLazyValue::as_array/as_object on an unparsed value

[yuxi-liu-wired]

fix: as_array/as_object on an unparsed OwnedLazyValue panicked on use

OwnedLazyValue::as_array and as_object (the &self versions from
JsonContainerTrait) return a LazyArray / LazyObject view of a
value that is still LazyPacked::Raw; the parse is cached in
LazyRaw::parsed. Their Deref impls only handled Parsed, so the
first use of the view panicked:

let lv: OwnedLazyValue = sonic_rs::from_str("[1,2]")?;
lv.as_array().unwrap().len()
    panicked: internal error: entered unreachable code:
              must be a lazy array

(The _mut versions replace Raw with Parsed first, so they work,
which is the path the existing tests use.) Deref now also takes the
Raw case and returns the cached parse from LazyRaw::load.

Test: test_owned_as_array_as_object_on_raw (fails before this
change); cargo miri test --all-features --lib lazyvalue::owned is
clean.

Testing

Each commit adds a regression test that fails before the change. The full test suite passes and
cargo fmt --check is clean on the changed files.

Found with a differential fuzzer comparing serde_json, simd-json, sonic-rs and jiter.

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[codecov]

Codecov Report

❌ Patch coverage is 76.47059% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 72.88%. Comparing base (cd1e5ab) to head (b46a8e0).

Files with missing lines	Patch %	Lines
src/lazyvalue/owned.rs	76.47%	8 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #254      +/-   ##
==========================================
+ Coverage   72.62%   72.88%   +0.25%     
==========================================
  Files          42       42              
  Lines        9934     9962      +28     
==========================================
+ Hits         7215     7261      +46     
+ Misses       2719     2701      -18     

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