feature-e2e

Run an end-to-end test of a Product CLI feature in a fresh tmp directory. Build the release binary, init a clean .product/ project, then exercise every CLI command the feature adds — including the existing commands the feature touches — against the new repo. Use when the user asks to "do an end-to-end test of FT-XXX", "verify FT-XXX works in a fresh repo", "test FT-XXX end to end", or "shake out FT-XXX from scratch".