fix(zulip): pass Platform enum instead of string to BasePlatformAdapter.__init__

Root cause of 'str' object has no attribute 'value' error during connect():
the adapter passed a raw string 'zulip' to the base class's platform
parameter, which expects a Platform enum instance. When self.name was
accessed (calling self.platform.value.title()), the string had no .value
attribute.

Fix: import Platform from gateway.config and wrap with Platform('zulip').

plugins/platforms/zulip/adapter.py

@@ -43,7 +43,7 @@ except ImportError:
     HTTPX_AVAILABLE = False
     httpx = None
 
-from gateway.config import PlatformConfig
+from gateway.config import Platform, PlatformConfig
 from gateway.platforms.base import (
     BasePlatformAdapter,
     MessageEvent,
@@ -118,8 +118,8 @@ class ZulipAdapter(BasePlatformAdapter):
     """
 
     def __init__(self, config: PlatformConfig):
-        platform_name = "zulip"
-        super().__init__(config=config, platform=platform_name)
+        platform = Platform("zulip")
+        super().__init__(config=config, platform=platform)
 
         extra = config.extra or {}