feat(stt): add FunASR / SenseVoice provider (#16473)

### Summary

Adds FunASR as a self-hosted speech-to-text provider through its
OpenAI-compatible `/v1/audio/transcriptions` endpoint.

This is a focused replacement for #15526 by @Rene0422 and relates to
#15448. The unrelated Markdown parser changes from the previous branch
are intentionally removed so this PR contains only the FunASR provider
integration.

- register FunASR as a `SPEECH2TEXT` factory;
- add `FunASRSeq2txt` with `sensevoice` and `http://localhost:8000/v1`
defaults, an optional API key, URL normalization, and inherited
transcription handling;
- wire FunASR into the current local-provider schema with a prefilled
local URL and official documentation link;
- discover the server's `/v1/models` dynamically and expose every
returned model as speech-to-text in the model picker;
- use RAGFlow's existing default provider icon fallback instead of
referencing a missing `funasr` asset;
- list FunASR in the supported-provider documentation;
- add focused backend and frontend regression tests.

### Validation

- focused backend pytest suite -> `7 passed`
- real CPU `funasr-server` + RAGFlow provider smoke test -> discovered
`fun-asr-nano`, `sensevoice`, and `paraformer`; transcribed a real WAV
as `我现在在录一段测试音频` (`10` tokens, `0.504s`)
- `ruff check` and `ruff format --check` on the changed Python files
- `python3 -m py_compile` on the provider and its test
- JSON parse and a semantic assertion for exactly one enabled FunASR
`SPEECH2TEXT` factory
- focused frontend Jest test -> `2 passed`
- ESLint and Prettier on all changed TypeScript files
- `npm run build` -> production build succeeded (`14,181` modules
transformed)
- `git diff --check`

### Deployment

Run FunASR separately and point the RAGFlow provider at it:

```bash
pip install funasr
funasr-server --device cuda --model sensevoice
```

The API key remains optional because the stock local server does not
require authentication. A key can still be supplied when the endpoint is
protected by a gateway.

---------

Signed-off-by: LauraGPT <LauraGPT@users.noreply.github.com>
Co-authored-by: LauraGPT <LauraGPT@users.noreply.github.com>

test/unit_test/rag/llm/test_model_meta_funasr.py

@@ -0,0 +1,55 @@
+#
+#  Copyright 2026 The InfiniFlow Authors. All Rights Reserved.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+#
+
+import pytest
+
+from common.constants import LLMType
+from rag.llm.model_meta import FunASR
+
+
+pytestmark = pytest.mark.p2
+
+
+def test_funasr_formats_server_models_as_speech_to_text():
+    provider = FunASR(api_key="", base_url="http://localhost:8000/v1")
+
+    models = provider._format_model_list(
+        {
+            "object": "list",
+            "data": [
+                {"id": "fun-asr-nano", "object": "model"},
+                {"id": "sensevoice", "object": "model"},
+                {"object": "model"},
+            ],
+        }
+    )
+
+    assert models == [
+        {"name": "fun-asr-nano", "model_types": [LLMType.ASR.value], "features": [], "max_tokens": 8192},
+        {"name": "sensevoice", "model_types": [LLMType.ASR.value], "features": [], "max_tokens": 8192},
+    ]
+
+
+def test_funasr_rejects_malformed_model_lists():
+    provider = FunASR(api_key="", base_url="http://localhost:8000/v1")
+
+    assert provider._format_model_list({}) == []
+    assert provider._format_model_list({"data": "sensevoice"}) == []
+
+
+def test_funasr_uses_openai_compatible_models_endpoint():
+    assert FunASR(api_key="", base_url="http://localhost:8000/v1")._get_model_list_url() == "http://localhost:8000/v1/models"
+    assert FunASR(api_key="", base_url="http://localhost:8000")._get_model_list_url() == "http://localhost:8000/v1/models"

test/unit_test/rag/llm/test_sequence2txt_funasr.py

@@ -0,0 +1,74 @@
+#
+#  Copyright 2026 The InfiniFlow Authors. All Rights Reserved.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+#
+
+from types import SimpleNamespace
+from unittest.mock import MagicMock, patch
+
+import pytest
+
+from rag.llm.sequence2txt_model import FunASRSeq2txt
+
+
+pytestmark = pytest.mark.p2
+
+
+@patch("rag.llm.sequence2txt_model.OpenAI")
+def test_funasr_defaults_to_local_sensevoice(mock_openai):
+    provider = FunASRSeq2txt(key="")
+
+    mock_openai.assert_called_once_with(api_key="funasr", base_url="http://localhost:8000/v1")
+    assert provider._FACTORY_NAME == "FunASR"
+    assert provider.model_name == "sensevoice"
+    assert provider.base_url == "http://localhost:8000/v1"
+
+
+@patch("rag.llm.sequence2txt_model.OpenAI")
+def test_funasr_forwards_custom_connection_settings(mock_openai):
+    provider = FunASRSeq2txt(
+        key="local-secret",
+        model_name="paraformer",
+        base_url="http://funasr.internal:9000",
+    )
+
+    mock_openai.assert_called_once_with(api_key="local-secret", base_url="http://funasr.internal:9000/v1")
+    assert provider.model_name == "paraformer"
+
+
+@patch("rag.llm.sequence2txt_model.OpenAI")
+def test_funasr_empty_base_url_uses_local_default(mock_openai):
+    FunASRSeq2txt(key=None, base_url="")
+
+    mock_openai.assert_called_once_with(api_key="funasr", base_url="http://localhost:8000/v1")
+
+
+@patch("rag.llm.sequence2txt_model.OpenAI")
+def test_funasr_transcription_uses_openai_compatible_endpoint(mock_openai, tmp_path):
+    audio_path = tmp_path / "sample.wav"
+    audio_path.write_bytes(b"RIFF-test-audio")
+
+    client = MagicMock()
+    client.audio.transcriptions.create.return_value = SimpleNamespace(text="  hello from FunASR  ")
+    mock_openai.return_value = client
+    provider = FunASRSeq2txt(key="", model_name="sensevoice")
+
+    with patch("rag.llm.sequence2txt_model.num_tokens_from_string", return_value=4):
+        text, token_count = provider.transcription(audio_path)
+
+    assert text == "hello from FunASR"
+    assert token_count == 4
+    call = client.audio.transcriptions.create.call_args
+    assert call.kwargs["model"] == "sensevoice"
+    assert call.kwargs["file"].closed