Validate the Vjsc Vite Development Workflow

## Context The canonical Skin compiler now has a Vite plugin and a development preview in `packages/skins`. Before the generated Skins become the package source of truth, the repository needs an explicit integration boundary proving that canonical markup and styles behave correctly during development and production builds. The current preview exercises the Default Video Skin through React and compiled vanilla CSS. This issue expands that proof without moving the preview into the broader E2E suite prematurely. ## Scope - Exercise Default and Minimal Video Skins. - Exercise React and HTML targets. - Exercise Tailwind and vanilla CSS style output. - Verify both the Vite development server and production build. - Verify updates to canonical TSX, style modules, theme inputs, and compiler configuration. - Verify virtual CSS replacement, dependency watching, diagnostics, and source locations. - Keep the development matrix easy to select and inspect in `packages/skins`. ## Acceptance criteria - [ ] Every supported Skin, framework, and style combination can be selected and rendered in the development environment. - [ ] Editing canonical component source updates the active preview without restarting Vite. - [ ] Editing referenced style or theme source replaces the emitted CSS without retaining stale rules. - [ ] Compiler configuration changes are observed consistently. - [ ] Compiler warnings and errors identify the source module and location. - [ ] The production Vite build succeeds for the same configurations. - [ ] Focused integration coverage detects regressions in plugin transforms, emitted CSS, and watched dependencies. ## Required context - #2183 - #1972 - #1973 - `packages/compiler/src/bundlers/vite.ts` - `packages/skins/vite.config.ts` - `packages/skins/dev/`