fix: scroll bar incorrect behaviour in certain circumstances

[baiyuanneko]

Since I added the scrollbar feature to the track list page, I noticed an issue: after dragging the scrollbar with the left mouse button, using the mouse wheel would cause the scrollbar to jump back to the far left.
This pull request fixes that problem.

Summary by Sourcery

Fix scrollbar jumping by synchronizing the smooth scroll controller’s internal value with external scroll events and cleaning up listeners

Bug Fixes:

• Prevent scrollbar from snapping back after dragging by syncing the lerp controller value on external scrolls

Enhancements:

• Expose LerpController.isAnimating and add syncValue method for manual value updates

Chores:

• Remove scroll listener on dispose to avoid potential memory leaks

[sourcery-ai]

Reviewer's guide (collapsed on small PRs)

Reviewer's Guide

Introduce external scroll event handling in SmoothScrollController and extend LerpController to support direct value synchronization, ensuring the scrollbar’s position remains in sync after mouse interactions.

Sequence diagram for external scroll event handling in SmoothScrollController

sequenceDiagram
participant User as actor User
participant Scrollbar
participant SmoothScrollController
participant LerpController

User->>Scrollbar: Drag scrollbar (mouse down/move)
Scrollbar->>SmoothScrollController: Update offset
SmoothScrollController->>LerpController: syncValue(offset) (if not animating)
User->>Scrollbar: Use mouse wheel
Scrollbar->>SmoothScrollController: Update offset
SmoothScrollController->>LerpController: syncValue(offset) (if not animating)

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Class diagram for updated SmoothScrollController and LerpController

classDiagram
class SmoothScrollController {
  +void smoothScrollBy(double delta)
  +void dispose()
  +void _handleExternalScroll()
}
SmoothScrollController --|> ScrollController
SmoothScrollController o-- LerpController : uses

class LerpController {
  +void syncValue(double value)
  +bool isAnimating
  +double get value
}

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File-Level Changes

Change	Details	Files
Sync SmoothScrollController offset to LerpController on external scroll	Add listener in constructor for external scroll events Implement _handleExternalScroll to update controller when not animating Remove listener in dispose to prevent leaks	lib/widgets/smooth_horizontal_scroll.dart
Expose LerpController sync and animation state APIs	Add syncValue(double) to set internal value Introduce isAnimating getter based on ticker state	lib/utils/lerp_controller.dart

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[sourcery-ai]

Hey there - I've reviewed your changes and they look great!

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[Losses]

Cool, LGTM, Thanks!