fix: MIDI rearrange tool spec double-wrapped, AI returns _unknown

REARRANGE_TOOL_SPEC already has {type:'function', function:{...}}
wrapper. callLLM's tools.map(t => ({type:'function', function:t}))
added ANOTHER wrapper, creating nested:
  {type:'function', function:{type:'function', function:{name}}}
which AI models couldn't parse -> function name became _unknown.
Fix: pass .function (inner spec) instead of the outer wrapper.

app/static/js/app.jsx

@@ -13941,7 +13941,7 @@ const App = () => {
             apiKey,
             baseUrl: baseUrl.replace(/\/chat\/completions$/, '').replace(/\/$/, ''),
             messages,
-            tools: [window.AIGateway.REARRANGE_TOOL_SPEC],
+            tools: [window.AIGateway.REARRANGE_TOOL_SPEC.function],
             toolChoice: 'auto'
           });