feat(vulkan): Map Vulkan features to WebGPU features

[kolkov]

Problem

Adapter.Features() returns 0 - no features are reported to the user.

Location

hal/vulkan/api.go:195

Impact

• Users cannot query GPU feature support
• Feature-gated functionality unavailable
• Basic rendering works, advanced features not accessible

Solution

Implement featuresFromPhysicalDevice() similar to DX12 pattern in hal/dx12/adapter.go:204-223.

Map ~20 Vulkan features:

• TextureCompressionBC/ETC2/ASTC
• DepthClamp → DepthClipControl
• DrawIndirectFirstInstance
• ShaderFloat64
• etc.

Reference

• wgpu-rs: wgpu-hal/src/vulkan/adapter.rs:584-829 (~250 lines)
• DX12 pattern: hal/dx12/adapter.go:204-223

Priority

P2 - Target v0.5.0