Private Lobbies: Add kick player functionality (#1436)

## Description:
Added player management features so lobby hosts can kick players from
private games. This includes both UI changes and backend work.

### What's new:
- Hosts can now kick players from private lobbies with a simple button
- Added host badges and remove buttons to the UI
- Made sure only hosts can kick people, and hosts can't kick themselves

### How it works:
- When someone creates a private game, they automatically become the
host
- Kicking happens through WebSocket "kick-player" events
- Server checks that you're actually the host before letting you kick
anyone

<img width="1291" height="871" alt="Screenshot 2025-07-15 002114"
src="https://github.com/user-attachments/assets/ea575f83-a0f4-45d1-9cfe-7521d373f3d5"
/>



### Known Issues:
- Kicked player gets general message (same when kicked for multi tab)

### Other Issues:
- Host abandoment still existent (host clicks on x; or is closing tab)

## Please complete the following:

- [x] I have added screenshots for all UI updates
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [x] I have added relevant tests to the test directory
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced
- [x] I have read and accepted the CLA agreement (only required once).

## Please put your Discord username so you can be contacted if a bug or
regression is found:

[UN]nvm

---------

Co-authored-by: floriankilian <floriankilian@users.noreply.github.com>

src/client/styles.css

@@ -251,15 +251,15 @@ label.option-card:hover {
 }
 
 .player-tag {
-  display: flex;
+  display: inline-flex;
   align-items: center;
-  justify-content: center;
-  background: rgba(255, 255, 255, 0.1);
-  padding: 4px 16px;
+  gap: 8px;
+  background: #2a2a2a;
+  color: #fff;
+  padding: 8px 12px;
+  margin: 4px;
   border-radius: 16px;
   font-size: 14px;
-  color: #fff;
-  border: 1px solid rgba(255, 255, 255, 0.2);
 }
 
 #bots-count,
@@ -625,18 +625,6 @@ label.option-card:hover {
   padding: 0 16px;
 }
 
-.player-tag {
-  display: flex;
-  align-items: center;
-  justify-content: center;
-  background: rgba(255, 255, 255, 0.1);
-  padding: 4px 16px;
-  border-radius: 16px;
-  font-size: 14px;
-  color: #fff;
-  border: 1px solid rgba(255, 255, 255, 0.2);
-}
-
 /* News Button Notification */
 news-button .active button {
   position: relative;
@@ -670,3 +658,28 @@ news-button .active button::after {
     transform: scale(1.4);
   }
 }
+
+.host-badge {
+  font-size: 11px;
+  color: #4caf50;
+  font-weight: bold;
+}
+
+.remove-player-btn {
+  width: 16px;
+  height: 16px;
+  border: none;
+  background: #ff4444;
+  color: white;
+  border-radius: 50%;
+  font-size: 11px;
+  cursor: pointer;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  margin-left: 4px;
+}
+
+.remove-player-btn:hover {
+  background: #ff6666;
+}