### What problem does this PR solve?
The Go model-driver layer () has ~38,700 lines across 109 files. Roughly
74% of that is boilerplate duplicated into every driver: identical HTTP
client setup, the same 65-line SSE scanner loop, and 10-11 one-line "not
supported" stub methods per driver. Any fix must be manually propagated
to every file. Closes#15820.
This PR establishes the three shared utility files that form the
foundation for incremental driver migration:
---
### Type of change
- [x] New Feature (non-breaking change which adds functionality)
- [x] Refactoring
---------
Co-authored-by: Haruko386 <tryeverypossible@163.com>
## Summary
- Harden `NewN1NModel` to avoid panics when `http.DefaultTransport` is a
custom non-`*http.Transport` RoundTripper.
- Fallback to a safe transport (`ProxyFromEnvironment`) while preserving
existing pooling/timeout settings.
- Add `n1n_test.go` with coverage for name/factory plus
`TestN1NNewModelWithCustomDefaultTransport`.
Co-authored-by: Cursor <cursoragent@cursor.com>
### What problem does this PR solve?
Add a Go driver for **n1n.ai** (https://docs.n1n.ai), one of the
unchecked providers on the umbrella tracking issue #14736. n1n.ai is an
OpenAI-compatible aggregator hosting a 450+ model catalog (GPT, Claude,
Gemini, DeepSeek, Kimi, Qwen, embedding + reranker families) under
`https://api.n1n.ai/v1`.
Until this PR, a tenant who configured `n1n` as a model provider in the
Go layer fell through to the default branch of
`internal/entity/models/factory.go` and got the dummy driver.
---------
Co-authored-by: sxxtony <sxxtony@users.noreply.github.com>
