revert: remove user chat (direct + groups) from the pet window

Reverts 21a042d, 0d3e92c, 0016b6a, c797e98, 03ebea1. Keeps the pet's
own-sessions scope, status bar mine=1, scroll speed and the health hover card.
The chat_* tables and <data dir>/chat/ files are left in place (unused).

client/src/components/Sagi/sagi.css

@@ -6,8 +6,7 @@
  * infinite animation makes the browser draw a new frame 60 times a second for
  * as long as the page is open (the drop-shadow filter re-rendered each time),
  * which made the whole desktop stutter. All motion is disabled under
- * [data-reduced="1"] and prefers-reduced-motion. The blue dot counts unread
- * chat messages from other users (server mode).
+ * [data-reduced="1"] and prefers-reduced-motion.
  * Transform origins are the delicate part - see the comments on .sagi-avatar
  * and .sagi-eye-blink for which reference box each one resolves against.
  * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
@@ -407,25 +406,6 @@
   outline: 2px solid #818cf8;
   outline-offset: 3px;
 }
-/* Unread chat messages from other users: top-left, opposite the error dot. */
-.sagi-chat-dot {
-  position: absolute;
-  top: 2px;
-  left: 2px;
-  min-width: 14px;
-  height: 14px;
-  padding: 0 2px;
-  border-radius: 9999px;
-  background: #3b82f6;
-  color: #fff;
-  font-size: 9px;
-  font-weight: 700;
-  display: flex;
-  align-items: center;
-  justify-content: center;
-  border: 2px solid #0c0c14;
-}
-
 .sagi-error-dot {
   position: absolute;
   top: 2px;