[Model] Add IndexTTS2 text-to-speech support (#3838)

Signed-off-by: BeatSeat <wendavid552@gmail.com>
Signed-off-by: David <david@podcast.ai>
Signed-off-by: wendavid552 <wendavid552@gmail.com>
Signed-off-by: WenDavid <davidzhangcf@foxmail.com>

vllm_omni/core/sched/omni_scheduling_coordinator.py

@@ -51,6 +51,9 @@ _FULL_PAYLOAD_INPUT_STAGES: frozenset[tuple[str, str]] = frozenset(
         ("Qwen3TTSCode2Wav", "code2wav"),
         # cosyvoice3: cosyvoice3_talker (Stage 0) -> cosyvoice3_code2wav (Stage 1).
         ("CosyVoice3Model", "cosyvoice3_code2wav"),
+        # indextts2: indextts2_talker (Stage 0) -> indextts2_s2mel_decoder
+        # (Stage 1). Stage 1 consumes the complete mel/latent payload.
+        ("IndexTTS2S2MelDecoder", "indextts2_s2mel_decoder"),
         # dynin: token2text (Stage 0) -> token2image (Stage 1) ->
         # token2audio (Stage 2).  Producer wires via
         # custom_process_next_stage_input_func: *_full_payload in deploy yaml.