perf: use type guards to avoid descending into nodes

[Stranger6667]

No description provided.

[codecov]

Codecov Report

❌ Patch coverage is 97.79412% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 93.23%. Comparing base (5f2e617) to head (19c7134).

Files with missing lines	Patch %	Lines
crates/jsonschema/src/types.rs	93.33%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #863      +/-   ##
==========================================
+ Coverage   93.21%   93.23%   +0.02%     
==========================================
  Files          87       87              
  Lines       15376    15500     +124     
==========================================
+ Hits        14332    14452     +120     
- Misses       1044     1048       +4     

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[codspeed-hq]

CodSpeed Performance Report

Merging #863 will degrade performances by 97.59%

_{Comparing dd/type-guards (b847dfd) with master (5f2e617)}

Summary

⚡ 1 improvement
❌ 3 regressions
✅ 57 untouched

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	BASE	HEAD	Change
⚡	is_valid[FHIR/Fhir]	146.7 µs	130.7 µs	+12.2%
❌	is_valid[GeoJSON/Canada]	9.9 ms	17.2 ms	-42.41%
❌	validate[FHIR/Fhir]	147.4 µs	6,121.4 µs	-97.59%
❌	validate[GeoJSON/Canada]	9.9 ms	17.2 ms	-42.41%