fix(models): align minimax and zai defaults (#2445)

Update the coding-agent default model picks for ZAI, Cerebras,
and MiniMax so new sessions prefer the current model lineup.

Add the missing MiniMax-M2.1-highspeed direct provider entries
and normalize MiniMax Anthropic-compatible context limits so the
catalog matches the provider's supported model set.

packages/coding-agent/test/model-resolver.test.ts

@@ -378,6 +378,13 @@ describe("default model selection", () => {
 		expect(defaultModelPerProvider["openai-codex"]).toBe("gpt-5.4");
 	});
 
+	test("zai, minimax, and cerebras defaults track current models", () => {
+		expect(defaultModelPerProvider.zai).toBe("glm-5");
+		expect(defaultModelPerProvider.minimax).toBe("MiniMax-M2.7");
+		expect(defaultModelPerProvider["minimax-cn"]).toBe("MiniMax-M2.7");
+		expect(defaultModelPerProvider.cerebras).toBe("zai-glm-4.7");
+	});
+
 	test("ai-gateway default is opus 4.6", () => {
 		expect(defaultModelPerProvider["vercel-ai-gateway"]).toBe("anthropic/claude-opus-4-6");
 	});