feat(hint): targets, automatic hints and formatting

Target fields on the admin hints page. The dashboard shows the four
automatic hints after admin hints when their condition is true, using
data Core already serves. HintText renders **bold** and safe links (app
path or https) as React elements, never HTML, in hints and news.
Auto-close without tick hides for this session, X for 7 days, tick + X
for good.

README.md

@@ -118,7 +118,13 @@ To Be Played is split into three repositories:
   and menu opening. A request whose address is not confirmed shows "Not confirmed" and only a Delete button. The login tells a waiting user that the admin has not decided yet.
 - **Dashboard hints**: news from the admin at the bottom of the dashboard, one at a time. A "Dismiss" hint closes
   after 30 s or with X and comes back in the next browser session unless "Do not show again" is ticked; an
-  "Accept" hint stays until "OK". Admins write, preview and end hints on `/admin/hints` (Auth stores them).
+  "Accept" hint stays until "OK". Admins write, preview and end hints on `/admin/hints` (Auth stores them). A hint can
+  target groups (without Steam, role and higher, new users, empty library; all must match). Four automatic hints
+  (no Steam, empty library, pile grew this month, open link queue for auditors) show after the admin hints while
+  their condition is true; the Frontend checks it with Core's library summary, stats and link queue. X hides an
+  automatic hint for 7 days, "Do not show again" for good, the 30 s auto close only for this browser session.
+  Admins turn each on or off on `/admin/hints`. Hint and news text may use `**bold**` and `[text](url)` (an app
+  path or https; anything else stays plain text); `HintText` renders React elements, never HTML.
 - **What's new**: a dialog on the dashboard shows the news entries the user has not seen yet, newest first. "Got it"
   marks them seen in Auth; closing the dialog any other way shows them again on the next dashboard visit. `/whats-new`
   (menu) lists all entries and marks them seen. Admins publish, preview, edit and delete entries on `/admin/news`.