add-to-homescreen-flow-tests

Overview

The PWA install flow is a four-stage test surface per references/install-flow-reference.md: installability gate → beforeinstallprompt handshake → per-platform install path → post-install display-mode signal. Every team's install regression looks slightly different - a missing start_url, an icon resolution drift, a prompt() called without a user gesture - but the test surface is the same.

This builder produces the per-PWA install suite. Output is a Playwright spec file plus a coverage YAML matrix mapping each install criterion from [install-criteria] to its assertion. The contract itself - gate cells, event lifecycle, per-platform paths, and the full event timeline - lives in references/install-flow-reference.md; the workflow consumes it by emitting verification cells.