fix(shared): guard maxOutputTokens <= 0 in model settings compatibility (#3305)

When model metadata reports maxOutputTokens as 0 or negative, the
clamp logic would set maxTokens to 0 and break generation. Added
a positive-value guard so invalid metadata is ignored and the
user-requested maxTokens is preserved.

🤖 Generated with OhMyOpenCode assistance
https://github.com/code-yeongyu/oh-my-opencode

src/shared/model-settings-compatibility.ts

@@ -165,6 +165,7 @@ export function resolveCompatibleModelSettings(
   if (
     maxTokens !== undefined &&
     input.capabilities?.maxOutputTokens !== undefined &&
+    input.capabilities.maxOutputTokens > 0 &&
     maxTokens > input.capabilities.maxOutputTokens
   ) {
     changes.push({