feat(models): validate WebGPU FP32 model 1.0.1

[chenmohan123]

Summary

• add sanitized PP-DocLayoutV3 model 1.0.1 artifacts with validated WASM FP32 and WebGPU FP32 compatibility while leaving the SDK 1.0.4 default on model 1.0.0
• record CPU, WASM, and physical WebGPU seven-fixture parity evidence, including strict box, polygon, score, model, fixture, and output hashes
• harden the immutable model release gate so publication is bound to main, the validated commit SHA, an unused Git tag, and matching committed benchmark evidence

Validation

• pnpm verify
• 50 model-pipeline pytest tests
• node scripts/verify-release.mjs --models 1.0.0
• node scripts/verify-release.mjs --models 1.0.1
• physical WASM FP32 benchmark: 7/7, zero fallback
• physical WebGPU FP32 benchmark: 7/7, zero fallback

Release checkpoint

This PR does not publish model assets, change the SDK default manifest, tag an SDK release, or publish npm. Model publication remains gated on a separate explicit confirmation after merge to main.