feat(init): refresh design of Pages starter templates (#584)

## Summary

Replace the plain `void init` welcome pages with a shared Vite-style
layout for React, Vue, Svelte, and Solid, using Void colors, system
fonts, and automatic light/dark mode.

Preserve the original Pages-mode guidance and the database starters'
message list, form, API example, and seed instructions. Bundle a small
stack SVG and a theme-aware Void logo with `void`, with Vite attribution
embedded in the icon sprite.

Keep the shared starter styles in a CSS source file and inline the raw
CSS into the CLI bundle, with matching type declarations and build/test
configuration.

> [!IMPORTANT]
> This ships the SVG files with the core `void` package. I'm not a fan
of this but the starter code is already implemented within `void` and
since the SVG files are just a few KB + won't be bundled into a build,
it's not terrible.
>
> My preference would be to shift the starter code and assets into
`create-void`, but then `void init` will have to call `create-vite`,
creating a circular dep. Happy to do this in a follow-up PR.
> 
> Also, I'm not sure why `void init` needs to exist when there's
`create-void`. Maybe it can be removed?

## Examples

Screenshots from the four generated apps. React and Vue include
database-backed message forms; Svelte and Solid use Static Pages.

| React | Vue |
| --- | --- |
| ![React
starter](https://raw.githubusercontent.com/yangshun/void/0c6a519b9b0253785409f7fc7bd3fd1a6a555fe6/starters/react.jpg)
| ![Vue
starter](https://raw.githubusercontent.com/yangshun/void/0c6a519b9b0253785409f7fc7bd3fd1a6a555fe6/starters/vue.jpg)
|

| Svelte | Solid |
| --- | --- |
| ![Svelte
starter](https://raw.githubusercontent.com/yangshun/void/0c6a519b9b0253785409f7fc7bd3fd1a6a555fe6/starters/svelte.jpg)
| ![Solid
starter](https://raw.githubusercontent.com/yangshun/void/0c6a519b9b0253785409f7fc7bd3fd1a6a555fe6/starters/solid.jpg)
|

## Validation:

- `CI=true vp run test`: 734 test files and 14,499 tests passed; 31
tests skipped.
- `vp run check`: all 33 typecheck tasks passed.
- Targeted lint and formatting checks passed.
- Rebuilt CLI smoke test confirms generated `pages/style.css` matches
`starter-ui.css` byte-for-byte.
- Browser-verified the stack illustration and Void logo in light and
dark mode.

Author: yangshun

packages/void/package.json

@@ -20,6 +20,7 @@
     "docs",
     "schema.json",
     "skills",
+    "templates",
     "AGENTS_TEMPLATE.md",
     "README.md",
     "sandbox.Dockerfile"