docs(lab12): a QuickNotes endpoint as a WebAssembly component

[HNS2112]

Goal

Lab 12 submission: a Moscow-time endpoint built as a WebAssembly component with the Spin SDK, measured against the Lab 6 Docker container, plus the same logic rebuilt as a standalone WASI CLI module under wasmtime.

Changes

• wasm/moscow-time/ — Spin component: main.go, spin.toml, go.mod, wit/
• wasm-cli/ — standalone wasip1 module for wasmtime run
• evidence/lab12/ — build output, latency and cold-start measurements
• submissions/lab12.md — report covering Tasks 1–2 and the bonus

Testing

spin up serves valid Moscow-time JSON on /time; main.wasm is 5.24 MB.
Warm latency: Spin 10.5 ms vs Docker 11.3 ms. Cold start: Spin 137 ms vs Docker 140 ms.
CLI module 3.18 MB, 20.2 ms per wasmtime run invocation.

Note on toolchain

Spin 4's http-go template no longer uses TinyGo — it builds with componentize-go and SDK v3, so the lab's -buildmode=c-shared and TinyGo requirements describe the Spin 3.x pipeline. Four intermediate failures (a 404 in componentize-go's installer, a missing wit/ directory in the scaffold, a Go 1.26 linker segfault, and GOTOOLCHAIN silently upgrading Go) are documented in the report.

Checklist

• Title is a clear sentence (≤ 70 chars)
• Commits are signed (git log --show-signature)
• submissions/labN.md updated