Update Gradium endpoints to region-neutral URLs

Drop the EU-region default from the STT/TTS WebSocket URLs in favor of
the generic api.gradium.ai endpoint, and remove the explicit overrides
from the examples so they pick up the new defaults.

src/pipecat/services/gradium/stt.py

@@ -150,7 +150,7 @@ class GradiumSTTService(WebsocketSTTService):
         self,
         *,
         api_key: str,
-        api_endpoint_base_url: str = "wss://eu.api.gradium.ai/api/speech/asr",
+        api_endpoint_base_url: str = "wss://api.gradium.ai/api/speech/asr",
         encoding: str = "pcm",
         sample_rate: int | None = None,
         params: InputParams | None = None,
@@ -163,7 +163,7 @@ class GradiumSTTService(WebsocketSTTService):
 
         Args:
             api_key: Gradium API key for authentication.
-            api_endpoint_base_url: WebSocket endpoint URL. Defaults to Gradium's streaming endpoint.
+            api_endpoint_base_url: WebSocket endpoint URL.
             encoding: Base audio encoding type. One of "pcm", "wav", or "opus".
                 For PCM, the sample rate is appended automatically from the
                 pipeline's audio_in_sample_rate (e.g., "pcm" becomes "pcm_16000").

src/pipecat/services/gradium/tts.py

@@ -68,7 +68,7 @@ class GradiumTTSService(WebsocketTTSService):
         *,
         api_key: str,
         voice_id: str | None = None,
-        url: str = "wss://eu.api.gradium.ai/api/speech/tts",
+        url: str = "wss://api.gradium.ai/api/speech/tts",
         model: str | None = None,
         json_config: str | None = None,
         params: InputParams | None = None,