Fix publish for projects created before the production template

[twilson63]

Fixes the publish failure Tom hit in production: npm error Missing script: "build" during the Kaniko build.

Root cause: projects saved before #24 (or whose package.json the agent rewrote from the old template) have a dev-only package.json and no server.js/zepto-bridge.js — but the injected Dockerfile runs npm run build and node server.js.

Fix: preparePublishFiles() backfills the missing infrastructure into the publish payload client-side (where the template files are available): copies server.js/zepto-bridge.js from the current template when absent, and adds build/start scripts plus hyper-zepto/vite deps to package.json if missing. Anything the project already defines is left untouched; current-template projects pass through unchanged (identity, asserted byte-for-byte).

• 5 new unit tests; headless harness now publishes a legacy-shaped project and asserts the payload is deployable (9/9 checks green)
• Full suites green: 70 Gleam + 61 root vitest + 99 server vitest

🤖 Generated with Claude Code

[hyperio-mc]

Reviewed PR #26 — Fix publish for projects created before the production template. +179/-2 across 4 files. Already merged, but here's the review.

Root cause is clear: projects saved before #24 (or whose package.json the agent rewrote) have a dev-only package.json with no server.js/zepto-bridge.js — but the injected Dockerfile runs npm run build and node server.js. That's a Missing script: "build" crash at deploy time.

Fix is correct and minimal:

• preparePublishFiles() backfills missing infra client-side before the payload is sent: copies server.js and zepto-bridge.js from the current template when absent, and patches package.json to add build/start scripts + hyper-zepto/vite deps if missing.
• Everything the project already defines is left untouched — custom scripts, deps, and files are preserved. Current-template projects pass through byte-for-byte unchanged (identity test asserts this).
• Gracefully handles missing or unparseable package.json — just backfills the infra files, lets the build fail loudly instead of silently corrupting the payload.
• The preparedFiles() wrapper in publish.mjs uses dynamic import with a try/catch fallback, so if the module isn't available the publish still works with the raw files.

Tests:

• 5 unit tests covering legacy backfill, missing deps addition, identity (current template unchanged), custom scripts preserved, and broken JSON tolerance
• Headless harness now publishes a legacy-shaped project and asserts the payload contains server.js, zepto-bridge.js, build script, and start script (9/9 checks green)

Clean fix. Good call doing this client-side where template files are available rather than server-side.