fix: only log registration count when it changes (stop 3s spam)

bot.py

@@ -168,8 +168,12 @@ class GravityBot(commands.Bot):
             except (json.JSONDecodeError, OSError):
                 pass
 
-        if count:
-            logger.info(f"Loaded {count} conversation→project registrations")
+        # Only log when count changes
+        prev = getattr(self, '_last_reg_count', -1)
+        if count != prev:
+            self._last_reg_count = count
+            if count:
+                logger.info(f"Loaded {count} conversation→project registrations")
 
     # ─── Channel Management ──────────────────────────────────────────