posthog-migration-deep-dive

Migrate to PostHog from Google Analytics, Mixpanel, Amplitude, or Segment. Covers dual-write strategy, historical data import, event name mapping, identity resolution, and feature flag based traffic shifting. Trigger: "migrate posthog", "posthog migration", "switch to posthog", "posthog from mixpanel", "posthog from GA", "posthog replatform".