fix: use API name for published agents in preview picker @W-21258414@

[marcelinollano]

What does this PR do?

The preview picker was displaying published agents using their MasterLabel (friendly display name) instead of the DeveloperName (API name). This was inconsistent with other pickers (activate/deactivate, test run) which all use API names. This PR fixes the preview picker to use developerName for published agents, sorts agents by type (script first, then published) and alphabetically within each group, and adds unit tests.

What issues does this PR fix or reference?

@W-21258414@

Functionality Before

Published agents displayed their label name (e.g., "Guest Experience Agent") in the preview picker.

Functionality After

Published agents now display their API name (e.g., "Guest_Experience_Agent") in the preview picker, consistent with all other agent pickers. Agents are also sorted with script agents first, then published, alphabetically within each group.

Testing Setup Notes

Run the preview picker tests:

npx mocha test/commands/agent/preview/index.test.ts --require ts-node/register

To verify manually, run sf agent preview against an org with both published and script agents and confirm the picker shows API names and sorts correctly.

[EstebanRomero84]

QA Notes

I ran sf agent preview and verified that:

• Published agents display API name.

- Agent Script are displayed first.

• Agents are sorted alphabetically.