[with-developer]

Purpose

The additive items of #152:

• A transport that reports its losses, or sets the share of frames drawn in part from them, could not ask how many blocks of a frame had arrived.
• A program could learn a context's GPU only from a string meant for people.

Changes

• Reception counts.
  • Rust: Decoder::received_blocks and total_blocks.
  • The browser player: received_blocks and total_blocks, which scripts/check_web.mjs checks.
  • The C API: emberwave_decoder_reception fills an EmberwaveReception with the received and total blocks, and whether the start of frame header arrived.
• Context info. emberwave_context_info fills an EmberwaveContextInfo: the backend, the kind of device (EMBERWAVE_DEVICE_*), the PCI vendor and device, and which call made the context (EMBERWAVE_CONTEXT_KIND_*).
• Both structs carry struct_size (D69). The test of first sizes pins them: 24 and 16 bytes.
• Docs: the C API table and the browser player section of ARCHITECTURE.md, the C README, and CHANGELOG.md.

Testing

• Reception. A new C API test splits a frame into packets. The counts start at 0, the header arrives with the first packet, and the counts rise to the total. A short struct_size is refused.
• Context info. The same test checks a context's backend, device type and kind, and a NULL context. The Metal test checks that a context on the app's queue says Metal and kind Metal.
• Suite. cargo test --release --workspace on the M3 Max.
• Lints. Clippy for the workspace, wasm32 and Windows.
• Browser. scripts/build_web.sh and node scripts/check_web.mjs.

Benchmark impact

None.

Review

A small additive change built on the struct helpers reviewed in #153, so it was not sent to the review agent.

Related issue

#152 (items 20 and 22).