Add qwen3_next to tool call format inference

The Qwen3-Next family uses the same XML tool call format as Qwen3.5
but wasn't recognized by ToolCallFormat.infer(), so tool calls were
silently lost.

Fixes #161.

Author: alankessler

Libraries/MLXLMCommon/Tool/ToolCallFormat.swift

@@ -155,6 +155,11 @@ public enum ToolCallFormat: String, Sendable, Codable, CaseIterable {
             return .xmlFunction
         }
 
+        // Qwen3-Next family (qwen3_next, etc.)
+        if type.hasPrefix("qwen3_next") {
+            return .xmlFunction
+        }
+
         // Mistral3 family (mistral3, mistral3_text, etc.)
         if type.hasPrefix("mistral3") {
             return .mistral

Tests/MLXLMTests/ToolTests.swift

@@ -547,6 +547,11 @@ struct ToolTests {
         #expect(ToolCallFormat.infer(from: "qwen3_5_moe") == .xmlFunction)
         #expect(ToolCallFormat.infer(from: "QWEN3_5") == .xmlFunction)
 
+        // Qwen3-Next models (prefix matching)
+        #expect(ToolCallFormat.infer(from: "qwen3_next") == .xmlFunction)
+        #expect(ToolCallFormat.infer(from: "qwen3_next_moe") == .xmlFunction)
+        #expect(ToolCallFormat.infer(from: "QWEN3_NEXT") == .xmlFunction)
+
         // Mistral3 models (prefix matching)
         #expect(ToolCallFormat.infer(from: "mistral3") == .mistral)
         #expect(ToolCallFormat.infer(from: "Mistral3") == .mistral)