feat: expose baseline TrUAPI transport

[replghost]

Summary

• expose host_truapi_send and host_truapi_poll as baseline PolkaVM App ABI imports
• surface bounded opaque TrUAPI request/response queues through native, CoreVM, Wasm, and translated browser runtimes
• enforce 1 MiB frames, 32 queued frames, and 4 MiB per-direction byte budgets
• refresh source-built browser assets and prepare runtime version 0.1.2

Verification

• cargo test --workspace — 37 passed across 7 suites
• cargo clippy --workspace --all-targets -- -D warnings — passed
• npm test — browser package 5 passed; embedded assets byte-identical
• canonical runtime queue-bound tests cover frame count and byte limits

Extends paritytech/host-rust-core#540.