feat(desktop): add workbook performance recording tools

[myu404]

Summary

• Treat workbook performance recording as two independent, headless Desktop operations: start and stop.
• Route both tools through External Client API 0.2.14, validate the terminal recording path, and expose them in the dynamic-authoring profile.
• Add unattended direct MCP, backend agent, and headed agent UI smoke coverage.
• Bump the package version to 2.68.7.

Why

Agents need to control workbook performance recording without invoking the existing UI toggle. The returned workbook path remains an opaque path on the Tableau Desktop computer.

Verification

• npx --no-install vitest run src/tools/desktop/emittedToolReferences.test.ts src/desktop/externalApi/externalApiContract.test.ts src/desktop/externalApi/externalApiToolExecutor.test.ts src/desktop/wrappers/startPerformanceRecording.test.ts src/desktop/wrappers/stopPerformanceRecording.test.ts src/tools/desktop/api/startPerformanceRecording.test.ts src/tools/desktop/api/stopPerformanceRecording.test.ts src/server.desktop.test.ts src/server.desktop.schema-equivalence.test.ts src/tools/toolName.test.ts src/tools/desktop/paramOriginDescriptions.test.ts src/tools/desktop/structuredContentInvariant.test.ts --config ./vitest.config.ts
• npx vitest run --config scripts/smoke/workbook-performance-recording/vitest.config.mts

Review focus

• The tools require External Client API 0.2.14 and intentionally perform no MCP-side filesystem access.