### What problem does this PR solve?
Go: implement provider: PaddleOCR_Local
**Verified from CLI**
```
RAGFlow(user)> ocr with 'PaddleOCR-VL@test@paddleocr_local' file './internal/test1.jpg'
+----------------------+
| text |
+----------------------+
| ## Parallel to these |
+----------------------+
```
### Type of change
- [X] Bug Fix (non-breaking change which fixes an issue)
- [X] New Feature (non-breaking change which adds functionality)
- [X] Refactoring
### What problem does this PR solve?
implement rerank, asr, tts for TogetherAI
### Type of change
- [x] New Feature (non-breaking change which adds functionality)
### What problem does this PR solve?
Fixes#15015
The TogetherAI Go driver in `internal/entity/models/togetherai.go`
shipped a stub `Embed` method that returned `"TogetherAI, no such
method"`, so TogetherAI could not be used as an embedding provider in
RAGFlow. This PR fills that gap.
TogetherAI exposes a public OpenAI-compatible embeddings endpoint at
`POST https://api.together.ai/v1/embeddings` that accepts the standard
`{model, input}` shape with `Authorization: Bearer <api_key>` (confirmed
in TogetherAI's official docs:
https://docs.together.ai/docs/embeddings-overview). Documented embedding
models include `intfloat/multilingual-e5-large-instruct`,
`BAAI/bge-large-en-v1.5`, and `BAAI/bge-base-en-v1.5`.
### Changes
- `internal/entity/models/togetherai.go`: implement
`TogetherAIModel.Embed`.
- Validate inputs (api key, model name) and short-circuit on empty
texts.
- Resolve region with the existing `baseURLForRegion` helper.
- Build URL from `URLSuffix.Embedding`.
- Send `{model, input}` POST body, add `dimensions` when
`embeddingConfig.Dimension > 0` (matches the pattern in #14735).
- Bearer auth + JSON content type, mirroring the chat path.
- Parse `{data: [{embedding, index}]}` and reorder by `index`, rejecting
out-of-range indices, duplicates, and missing entries so the output
always lines up with the input. Same shape as the merged Mistral,
Upstage, and Novita Embed implementations.
- `conf/models/togetherai.json`:
- Add `"embedding": "embeddings"` to `url_suffix`.
- Add default embedding model entries for
`intfloat/multilingual-e5-large-instruct`, `BAAI/bge-large-en-v1.5`, and
`BAAI/bge-base-en-v1.5`.
### Type of change
- [x] New Feature (non-breaking change which adds functionality)
## What
- Add TogetherAI as a chat provider backed by its OpenAI-compatible
`/v1/chat/completions` API
- Register TogetherAI in the Go model factory and provider config
- Support non-streaming chat, SSE streaming chat, model listing, and
connection checks
## Notes
- Uses the current TogetherAI OpenAI-compatible base URL
`https://api.together.ai/v1`
- Forwards documented chat parameters from `ChatConfig`: `max_tokens`,
`temperature`, `top_p`, `stop`, and GPT-OSS `reasoning_effort`
- Routes Together reasoning traces from `reasoning` /
`reasoning_content` into `ReasonContent`
## Tests
- `go test -vet=off -run TestTogetherAI -count=1
./internal/entity/models`
- `go test -vet=off -count=1 ./internal/entity/models`
Refs #14736
