Fix Gemini Live session resumption hanging after reconnect

After a reconnect, _ready_for_realtime_input was never set back to True
because _create_initial_response (which sets the flag) is only called on
initial connection. This caused all audio/video/text to be silently
dropped after reconnecting, making the bot appear to hang.

Set the flag in _handle_session_ready when context already exists
(i.e. reconnect case) since we don't need to go through
_create_initial_response again.

src/pipecat/services/google/gemini_live/llm.py

@@ -1360,6 +1360,9 @@ class GeminiLiveLLMService(LLMService):
         if self._run_llm_when_session_ready:
             self._run_llm_when_session_ready = False
             await self._create_initial_response()
+        elif self._context:
+            # Reconnect case: context already exists, no need for _create_initial_response
+            self._ready_for_realtime_input = True
 
     async def _handle_msg_model_turn(self, msg: LiveServerMessage):
         """Handle the model turn message."""