add support for mixpanel for omi macOS; automatic events included

[beastoin]

what's included?

• tracking the automatic events ($ae_first_app_open, $ae_sesison, etc...) for omi macos

deps:

• mixpanel-flutter beastoin/mixpanel-flutter@f9234e9
• mixpanel-swift beastoin/mixpanel-swift@5fd6584

demo: #3484 (comment)

deploy:

• deploy macos app

notices: the macos lib is not officially supported by the mixpanel sdk; use it at your own risk.

#3455

[beastoin]

[gemini-code-assist]

Code Review

This pull request adds Mixpanel support for macOS by leveraging a forked version of mixpanel-flutter that includes native Swift bindings. The platform detection logic has been updated to use mixpanel-flutter on macOS, iOS, and Android, while falling back to mixpanel_analytics for other platforms like Windows. The changes look good and align with the goal of the PR. I've left one comment regarding the use of an SSH URL for a pod dependency in the Podfile, which should be changed to HTTPS for better build reliability.