Back office page titles and h1 headings

User story

As a user of the Janeway back office, I would like a consistent name for the pages that I'm visiting. Right now, not all the information is available in the places I'd like, in the structure I need for it to be accessible.

• I can see or hear the name of the page in the browser tab, which is good
  

• I can't see or hear the name of the site in the browser tab

• I can navigate to an h1 with the page title
  

• I am confused by another h1 with the site name
  

Proposed solution

• Agree on a standard format for the browser tab (HTML title) that includes both pieces of info, like Page name | Site name.
• Check extensions on the base template for usage of the existing title block.
• Implement a contextual title, accounting for press, journal, and repository sites, via a standard Django template element on the base template (see https://github.com/openlibhums/janeway/pull/4491 for an example of how we might do it).
• #4816
• Check usage of title-section to make sure we are not creating pages with an empty h1.

Start with the base template and its existing title block, then review extensions and title-section usages across press, journal, and repository sites; use PR #4491 as the referenced example. Confirm the standard HTML title format and ensure page headings are not empty or duplicated, while checking the relationship to issue #4816.