fix: override bus.presence._compute_status so bot shows online

Odoo 18's _compute_status treats future last_poll as MORE disconnected
(absolute delta). Override forces status='online' when last_poll > now,
which is set 24h ahead by _sync_bot_user_presence when the health check
passes.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

addons/activeblue_ai/models/ab_ai_bot.py

@@ -186,3 +186,14 @@ class AbAiBot(models.Model):
                 Presence.sudo().create(vals)
         except Exception as exc:
             _logger.warning('Could not update bot user presence: %s', exc)
+
+
+class BusPresenceBot(models.Model):
+    _inherit = 'bus.presence'
+
+    def _compute_status(self):
+        super()._compute_status()
+        now = fields.Datetime.now()
+        for record in self:
+            if record.last_poll and record.last_poll > now:
+                record.status = 'online'