Added news, the roadmap and beta known-issue markers

Now that the beta is live, a few things changed on the site.

• News: important Blizzard announcements, major bugs the community has found and site notices show up on the right of the home page. The full list is on the news page.
• Roadmap: the schedule from the beta to the Summer 2027 update is now on the home page, with the current stage highlighted.
• Beta known issues: talents and abilities Blizzard listed as bugged are flagged in the talent calculator and spellbook, and the Legacy panel error is noted on the Legacy calculator.
• The beta client pre-install guide was removed now that the beta is open.