Bundle preloads so imports work, and live-reload the renderer in dev

[ipfizz]

Two fixes from macOS-user field feedback, both confirmed genuine in the code and fixed.

import in a preload silently broke window.api (fix)

A preload is injected as a classic script (a WKUserScript and its WebKitGTK / WinCairo equivalents have no module mode), so a top-level import threw a SyntaxError that aborted the whole preload — silently taking window.api with it.

The preload is now bundled into a self-contained IIFE before injection, inlining its imports:

• Shared common/preload-bundle.ts → runtime main/api/preload.ts (bundles via Bun in dev; raises a clear error instead of failing silently) + bundlePreloadAssets wired into build-macos / build-windows / build-linux so a packaged app matches dev.
• Plain preloads still pass through verbatim (no subprocess).
• Proven end-to-end on the WinCairo engine: an import-using preload exposes window.api.

bunmaska dev restarted the whole app (reopening the window) on every save (feat)

The watcher now classifies each change — a TypeScript source (compiled into the main process) restarts; any other watched file is a renderer asset (page / CSS / preload) and live-reloads the window in place over the child's stdin. No more window churn for HTML/CSS edits.

• main/dev-reload.ts (app-side stdin reload listener) + a reload path in the supervisor.
• Proven end-to-end on the engine: a reload on stdin re-navigates the page with no restart.

Testing

• New unit tests (preload bundling, dev change-classification, reload dispatch) + two engine-gated Windows integration probes.
• validate:windows → 187 pass, 0 fail; type-check + lint clean.
• The logic is platform-agnostic (the macOS/Linux backends just receive the already-bundled preload string) — CI confirms macOS + Linux here.

Docs

Corrected the now-inaccurate "preload is injected verbatim, keep it plain JS" across the scaffold, examples, and website: preloads are bundled, so imports work — just keep them browser code (no Node APIs).