Add support for title templates

[abdrahmanrizk]

Description

Description

Currently, when setting page titles in Vike, we have to manually handle title templates for each page. Having built-in support for title templates would improve developer experience and provide a consistent way to handle page titles across the application.

Current Workaround

Currently, we have to manually concatenate titles:

config({
  title: `My Site | ${pageContext.config.meta?.title}`,
});

Proposed Solution

Add support for title templates similar to other meta frameworks. For example:

export default {
  meta: {
    titleTemplate: '%s | My Site', // or (title) => `${title} | My Site`
  }
}

Then in page components:

config({
  title: 'Articles', // Would automatically become "Articles | My Site"
})

[brillout]

Yes, that's would be nice. It's very much something we want to implement.

Also, I was thinking of adding a new config +name with a default +titleTemplate:

// Default +titleTemplate
function titleTemplate(pageContext) {
  const { title, name } = pageContext.config
  if (!name || !title) return null
  return `${title} | ${name}`
}

The +name config would also set <meta property="og:site_name" content="${pageContext.config.name}">.

Or maybe projectName instead of name to be less ambiguous.

WDYT? (Contribution/PR welcome in case that's something you'd be up to.)