refactor(client): 🔨 initialize provider plugins before rotation mode detection

Move provider plugin initialization earlier in the constructor to ensure they are available when building the provider rotation modes map. This prevents potential issues where rotation mode detection logic might need access to provider instances before they were initialized.

src/rotator_library/client.py

@@ -140,6 +140,10 @@ class RotatingClient:
         self.global_timeout = global_timeout
         self.abort_on_callback_error = abort_on_callback_error
 
+        # Initialize provider plugins early so they can be used for rotation mode detection
+        self._provider_plugins = PROVIDER_PLUGINS
+        self._provider_instances = {}
+
         # Build provider rotation modes map
         # Each provider can specify its preferred rotation mode ("balanced" or "sequential")
         provider_rotation_modes = {}
@@ -164,8 +168,6 @@ class RotatingClient:
             provider_plugins=PROVIDER_PLUGINS,
         )
         self._model_list_cache = {}
-        self._provider_plugins = PROVIDER_PLUGINS
-        self._provider_instances = {}
         self.http_client = httpx.AsyncClient()
         self.all_providers = AllProviders()
         self.cooldown_manager = CooldownManager()