Save user cohorts (using tags)

Allow users to save filtered groups of contacts (based on events and properties) as named "cohorts". This enables users to track and analyze the behavior of specific user groups over time.

Feature Behavior:

• Saved cohorts are accessible from a dropdown on the home page/dashboard

• Selecting a cohort from the dropdown updates dashboard metrics to reflect only that cohort's behavior

• Useful for comparing different user types, e.g. "discoverers" vs "reviewers", or "consultants" vs "companies"

Acceptance Criteria:

• Cohorts are listed in a dropdown on the home/dashboard

• Selecting a cohort filters the dashboard metrics to reflect that group only