chore: bump version to 0.1.61 and fix tests

- Update VERSION from 0.1.46 to 0.1.61
- Remove ForceHTTP2 tests for OpenAI OAuth client (ForceHTTP2 was removed)
- Update createOpenAIReqClient test to use new single-arg signature
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/cmd/server/VERSION

-0.1.46
+0.1.61

backend/internal/repository/req_client_pool_test.go

@@ -77,21 +77,9 @@ func TestGetSharedReqClient_ImpersonateAndProxy(t *testing.T) {
 	require.Equal(t, "http://proxy.local:8080|4s|true|false", buildReqClientKey(opts))
 }
 
-func TestCreateOpenAIReqClient_ForceHTTP2Enabled(t *testing.T) {
-	sharedReqClients = sync.Map{}
-	client := createOpenAIReqClient("https://auth.openai.com/oauth/token", "http://proxy.local:8080")
-	require.Equal(t, "2", forceHTTPVersion(t, client))
-}
-
-func TestCreateOpenAIReqClient_ForceHTTP2DisabledForHTTP(t *testing.T) {
-	sharedReqClients = sync.Map{}
-	client := createOpenAIReqClient("http://localhost/oauth/token", "http://proxy.local:8080")
-	require.Equal(t, "", forceHTTPVersion(t, client))
-}
-
 func TestCreateOpenAIReqClient_Timeout120Seconds(t *testing.T) {
 	sharedReqClients = sync.Map{}
-	client := createOpenAIReqClient("https://auth.openai.com/oauth/token", "http://proxy.local:8080")
+	client := createOpenAIReqClient("http://proxy.local:8080")
 	require.Equal(t, 120*time.Second, client.GetClient().Timeout)
 }