test: add remaining coverage tests (+148 tests)

[bug-ops]

Summary

• Add comprehensive tests for remaining coverage gaps
• Fix test assertions to match actual implementation behavior

Test Files Added/Modified

File	Tests	Module
object_pool_comprehensive.rs	52	object_pool.rs (50% → 60%+)
streaming_comprehensive.rs (pjs-wasm)	52	streaming.rs (54% → 60%+)
Extended optimization_service_comprehensive.rs	+20	optimization_service.rs (55% → 70%+)
Extended parser_simd_zero_copy_comprehensive.rs	+24	simd_zero_copy.rs (43% → 60%+)

Fixes

• Fixed Priority constant values (CRITICAL=100, HIGH=80, MEDIUM=50, LOW=25)
• Fixed SecurityConfig default max_depth (64, not 32)
• Fixed zero size limit behavior (ignored, uses default)
• Fixed ObjectPool zero capacity test (should_panic)
• Fixed Frame::patch tests to use valid non-empty patches

Test plan

• All 2026 tests pass locally
• Zero clippy warnings
• Code formatted with nightly
• CI tests pass on Ubuntu, macOS, Windows

[github-actions]

WASM Bundle Size Report

Target	Raw (KB)	Gzipped (KB)	Status
web	155	70	✓ PASS
nodejs	156	70	✓ PASS
bundler	155	70	✓ PASS

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.

@@            Coverage Diff             @@
##             main      #48      +/-   ##
==========================================
+ Coverage   76.48%   77.18%   +0.70%     
==========================================
  Files          68       68              
  Lines       16584    16584              
==========================================
+ Hits        12684    12801     +117     
+ Misses       3900     3783     -117     

Flag	Coverage Δ
unittests	77.18% <ø> (+0.70%)	⬆️

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see 3 files with indirect coverage changes

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[github-actions]

WASM Bundle Size Report

Target	Raw (KB)	Gzipped (KB)	Status
web	155	70	✓ PASS
nodejs	156	70	✓ PASS
bundler	155	70	✓ PASS