Reduce agent load in shell integration tests

[Copilot]

Shell integration tests were timing out on CI due to dispatcher initialization loading all 20+ agents at startup.

Changes

• defaultAgentProvider/data/config.test.json — New minimal config with only the 4 agents exercised by the test suite, all configured to run in-process (execMode: "dispatcher") to avoid child process spawn overhead:

  • chat, greeting — general Q&A and startup greeting
  • calendar — @config schema calendar test
  • list — shopping list CRUD test

• shell/src/main/instance.ts — When launched with --test, passes "test" as configName to both getDefaultAppAgentProviders and getIndexingServiceRegistry:

const configName = isTest ? "test" : undefined;
const indexingServiceRegistry =
    await getIndexingServiceRegistry(instanceDir, configName);
// ...
...getDefaultAppAgentProviders(instanceDir, configName),