fix(alert-timeline): make timeline scrollable with mouse wheel/trackpad

[breken-ai]

Fixes #6759.

Root cause

react-chrono renders nested overflow containers with zero scroll extent inside the timeline (the reporter documented this with DevTools measurements). Chrome latches wheel gestures onto the zero-extent scroll container under the cursor and never chains them to the real scroll container - the tremor Card with max-h-[500px] overflow-y-auto. Net effect: the wheel does nothing over the timeline.

Fix

One file: keep-ui/features/alerts/alert-detail-sidebar/ui/alert-timeline.tsx (+31/-2).

• The scroll container moves off the Card onto a plain inner div (timelineScrollRef) carrying the same max-h-[500px] overflow-y-auto.
• A non-passive wheel listener scrolls that div directly (scrollTop += e.deltaY) and calls preventDefault() only when the scroll position actually changed, so overscroll at either end still chains to the page.

A CSS-only override of react-chrono's styled-component class names was considered and rejected as too fragile across react-chrono upgrades.

Verification

Wheel-handler logic exercised in a real Chrome page with a DOM mirroring the reporter's measured structure (658px content in a 500px clipped container):

• wheel over the nested wrapper scrolls the container and prevents default
• at max scroll the event passes through unmodified (page chaining preserved)
• scrolling back up resumes correctly
• a container with no overflow ignores the gesture entirely (no scroll trap)

Not run: the full keep-ui build/test suite and a native-input repro - synthetic WheelEvent dispatch does not trigger native scrolling, so the no-handler side reflects the reporter's documented measurements rather than fresh native input. No tsc pass locally; the diff is confined to one component using the file's existing imports plus useEffect/useRef.

Built by breken, your AI support engineer - breken.ai - this one's on us.

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[shahargl]

@breken-ai u'll need to sign the CLA