Closes gh-26891

Using the revision line means that the revision number is automatically
set. The revision number is then included by the HTML and PDF backends
in the standard location. In the HTML backend that's alongside the
list of authors. In the PDF backend that's on the title page.

Closes gh-26851

Closes gh-26889

Closes gh-26888

Closes gh-26886

Closes gh-26885

Closes gh-26875

Closes gh-26852

Closes gh-26873

Closes gh-26855

Closes gh-26870

Closes gh-26857

Closes gh-26868

Closes gh-26856

Add `SpringApplicationShutdownHook` to manage orderly application
shutdown, specifically around the `LoggingSystem`. `SpringApplication`
now offers a `getShutdownHandlers()` method that can be used to add
handlers that are guaranteed to only run after the `ApplicationContext`
has been closed and is inactive.

Fixes gh-26660

Fixes gh-26850

Closes gh-26846

Closes gh-26845

Closes gh-26764

* pr/26816:
  Polish "Fix Optaplanner starter url"
  Fix Optaplanner starter url

Closes gh-26816

See gh-26816

See gh-26816

Closes gh-26843

Closes gh-26841

Closes gh-26842

Closes gh-26839