feat: skip the build phase when build-command is none

[kristof-siket]

Why

The Prisma Console's setup generator supports repos with no build script — a stock bun create elysia app runs its TypeScript source directly. The action's build phase always runs build-command (default npm run build), so those repos fail on error: Script not found "build". Once this ships, the generator will emit build-command: none for such repos.

What

• The exact input value none skips the build phase, in both deploy and destroy modes. The run logs build: skipped (build-command: none) and continues to install → deploy as before.
• Only the literal none skips. An empty value still falls back to the default npm run build, and any other value runs verbatim — a blank or mistyped command can never silently skip a build.
• The decision lives in a new build.mjs (selectBuildCommand), following the repo's pattern of small tested modules (composer.mjs, deployment.mjs); main.mjs executes on import, so the logic had to move to be unit-testable.
• action.yml and the README document the value (inputs table row plus one sentence in the phases paragraph).

Build-report phases stay consistent

A skipped build sends no report update of its own, and the report never gets stuck in the build phase: mapPhase sends the install phase as the server-side build phase, so the report is already in build before the build command would run — the build phase's own update in a normal run re-sends that same value. The deploy phase then advances the report to deploy exactly as before. The server-visible phase sequence (build → deploy → terminal state) is identical with and without the skip.

Tests

• node --test tests/*.test.mjs: 43 pass, 0 fail (5 new in tests/build.test.mjs: none skips, empty falls back to the default, other commands run verbatim, None and commands containing "none" do not skip).
• CI's syntax checks (node --check on main.mjs, post.mjs, credentials.mjs, plus the new build.mjs) and the action.yml sanity check pass.
• Offline end-to-end smoke of main.mjs with a stub bun and a dummy service token: deploy+none and destroy+none log the skip line and continue to the Composer step; a real build-command still runs in its ::group::build block; outcome succeeded in all three runs.

🤖 Generated with Claude Code