Keep bots inside the 18 player slots instead of colliding with corpses

A bot took the next unused client id with no upper bound, and the roster
only capped bots at MAX_HOST_BOTS (20). The lobby's Enemy and Friendly
Bots rules plus a `bot add`, or two `bot add` commands, could therefore
make more than 17 bots beside the host. Client ids are also entity
numbers, and the corpse ring starts at entity 18
(PLAYER_CORPSE_ENTITY_BASE), so bots 18 and up shared an entity number
with a corpse: the net layer rejected the snapshot entity as a
centity-number gap, and the end-of-match client data overran its 18 rows
(setclientmatchdata IndexOutOfRange).

Bots now claim ids 1..17 only, wrapping around to reuse freed ids, and
adding stops when every slot is taken.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/bots/src/roster.rs

@@ -5,6 +5,8 @@ use crate::controller::HostController;
 
 pub const MAX_HOST_BOTS: u32 = 20;
 
+const MAX_CLIENT_SLOTS: u32 = playerstate_iw4::PLAYER_CORPSE_ENTITY_BASE as u32;
+
 const BOT_NAMES: [&str; 52] = [
     "contextrot",
     "t.me/contextrot",
@@ -250,16 +252,12 @@ impl BotRoster {
     }
 
     fn claim_id(&mut self, taken: &[ClientId]) -> Option<ClientId> {
-        // Only `bots + taken` ids are spoken for, so one candidate more than
-        // that always turns up a free one.
-        let candidates = self
-            .bots
-            .len()
-            .saturating_add(taken.len())
-            .saturating_add(1);
-        for _ in 0..candidates {
+        for _ in 1..MAX_CLIENT_SLOTS {
+            if !(1..MAX_CLIENT_SLOTS).contains(&self.next_client) {
+                self.next_client = 1;
+            }
             let id = ClientId(self.next_client);
-            self.next_client = self.next_client.wrapping_add(1).max(1);
+            self.next_client += 1;
             if !taken.contains(&id) && !self.is_bot(id) {
                 return Some(id);
             }