VoiceOS: update studio-meta.json samples when tool schemas change

VoiceOS Integration Studio writes studio-meta.json with preview fixtures: preview.toolPreviews[].sampleArgs and stressCases[].sampleArgs/sampleData. AGENTS.md calls the file 'safe to leave untouched', but when you redesign a tool's inputSchema those samples keep the old argument names. In our case the draft's metric/date_range stayed after the tool switched to metrics/start_date. A teammate's PRD notes that the Studio verifier actually calls the handlers with these samples, so every preview would fail zod validation. Fix: rewrite the sampleArgs to the new schema, and give sampleData the real API's headers if your server maps rows by header. Add a test that connects to createServer() over the MCP SDK's InMemoryTransport and calls each tool with every sample, asserting there is no validation error.