Deprecate `--ai` flag in favor of `--integration`

[mnriem]

Summary

The --ai flag on specify init is the legacy way to select an integration. The newer --integration flag (with --integration-options) fully replaces it. --ai-commands-dir and --ai-skills already emit deprecation warnings, but --ai itself does not.

Proposed behavior

When --ai is used, emit a deprecation warning:

⚠️ --ai is deprecated and will be removed in v1.0.0. Use --integration <name> instead.

--ai continues to function until 1.0.0.

Acceptance criteria

• Using --ai emits a visible deprecation warning
• Warning suggests the --integration equivalent
• --ai still functions as before (non-breaking)

[dhilipkumars]

these are all big and somewhat breaking changes @mnriem should these be organized as a github project and does it make sense to develop in a feature branch?

[mnriem]

That is why they are all first deprecation and then breaking at 1.0.0 time. So I am giving it some time. And the scope is not as big as you think. You have already been using --integration you just did not know it.

[dhilipkumars]

okay cool that makes sense, feel free to assign any ticket to me. Happy to help will have some cycles next week.