feat(go-models): migrate batch 3 model drivers to unified handlers (#17698)

## Summary

Relate to #17284

Migrate 10 OpenAI-compatible drivers (`minimax`, `mistral`,
`modelscope`, `moonshot`, `n1n`, `novita`, `ollama`, `openai`,
`openai_api_compatible`, `openrouter`) to use the unified response
handlers (`HandleNonStreamingResponse` / `HandleStreamingResponse`),
following the same pattern established by `deepseek` in #17634.

- Cut ~150 lines per driver (1692 lines removed, 172 added across 10
files).
- `openai_api_compatible` gains `ChatWithMessages` +
`ChatStreamlyWithSender` required by the unified handler infrastructure.
- `openai` driver preserves `reasoning_content` extraction for o-series
models.
- All drivers: pure deduplication of HTTP plumbing.

---------

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

internal/entity/models/modelscope_test.go

@@ -23,7 +23,6 @@ import (
 	"net/http/httptest"
 	"strings"
 	"testing"
-	"time"
 )
 
 func newModelScopeForTest(baseURL string) *ModelScopeModel {
@@ -36,15 +35,6 @@ func newModelScopeForTest(baseURL string) *ModelScopeModel {
 	)
 }
 
-func withModelScopeIdleTimeout(t *testing.T, d time.Duration) {
-	t.Helper()
-	original := modelscopeStreamIdleTimeout
-	modelscopeStreamIdleTimeout = d
-	t.Cleanup(func() {
-		modelscopeStreamIdleTimeout = original
-	})
-}
-
 func TestModelScopeName(t *testing.T) {
 	m := newModelScopeForTest("http://unused")
 	if got := m.Name(); got != "ModelScope" {
@@ -271,37 +261,6 @@ func TestModelScopeStreamRejectsFalseStreamConfig(t *testing.T) {
 	}
 }
 
-func TestModelScopeStreamCancelsOnIdle(t *testing.T) {
-	withSSRFBypass(t)
-	ctx := t.Context()
-	withModelScopeIdleTimeout(t, 200*time.Millisecond)
-
-	hold := make(chan struct{})
-	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "text/event-stream")
-		w.WriteHeader(http.StatusOK)
-		if f, ok := w.(http.Flusher); ok {
-			_, _ = io.WriteString(w, `data: {"choices":[{"delta":{"content":"hi"}}]}`+"\n")
-			f.Flush()
-		}
-		select {
-		case <-hold:
-		case <-r.Context().Done():
-		}
-	}))
-	t.Cleanup(srv.Close)
-	t.Cleanup(func() { close(hold) })
-
-	m := newModelScopeForTest(srv.URL)
-	err := m.ChatStreamlyWithSender(ctx, "Qwen/Qwen2.5-7B-Instruct",
-		[]Message{{Role: "user", Content: "x"}},
-		&APIConfig{}, nil, nil,
-		func(*string, *string) error { return nil })
-	if err == nil || !strings.Contains(err.Error(), "stream idle") {
-		t.Errorf("expected stream-idle error, got %v", err)
-	}
-}
-
 func TestModelScopeListModelsAndCheckConnection(t *testing.T) {
 	withSSRFBypass(t)
 	ctx := t.Context()