feat(analytics): add feed_type to Playback: Play events from the feed

[dylanjeffers]

Description

Adds a feed_type property to Playback: Play analytics events for plays originating from the feed lineup, so engagement on the "For You" vs "Latest" feed can be measured separately. Values match the view property of Feed: Change view (FOR_YOU / LATEST).

How it works

• PlaybackTrack queue entries get an optional feedType, stamped by TrackLineup when the feed page builds the queue (same pattern as the existing collectionId analytics field). Snapshotting at queue time means passive plays (queue auto-advance via next/previous) report the view the track actually came from, even if the user switches tabs mid-playback.
• The playback saga (watchNext/watchPrevious) attaches feed_type to the source: passive PLAYBACK_PLAY events via a new getFeedType selector.
• Track-tile plays on the feed page (source: track tile lineup) include feed_type directly from the active tab.
• Both desktop and mobile-web feed pages pass feedType={feedTab} to TrackLineup.
• Non-feed lineups are unchanged — the property is only present when the queue entry came from the feed. Recommended-track autoplay entries appended after the feed queue runs dry correctly do not carry it.

Note: CHRONOLOGICAL no longer exists in the FeedTab enum (it was migrated to LATEST), so new events emit only FOR_YOU / LATEST.

Purely analytics instrumentation — no UI changes.

Testing

• npm run typecheck clean in packages/common and packages/web
• eslint clean on all changed files
• Not verified end-to-end in a browser (requires an authenticated session with a populated feed); worth a spot-check in Amplitude dev after merge

🤖 Generated with Claude Code

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