feat: add tutorial help component for video trimming guidance

[ateendra24]

Pull Request Template

Description

Added a "How trimming works" help button to the timeline editor toolbar. This button opens a dialog containing a tutorial placeholder, a clear textual explanation, and a visual diagram illustrating that the red trim regions represent the parts of the video that will be removed during export.

Motivation

New users were finding the Trim tool confusing, often mistaking the red selection for the portion of the video to be kept. This addition provides immediate, in-context help to clarify that the red regions mark segments for deletion, improving the user onboarding experience and reducing export errors.

Type of Change

• New Feature
• Bug Fix
• Refactor / Code Cleanup
• Documentation Update
• Other (please specify)

Related Issue(s)

#34

Screenshots / Video

Screenshot :

Testing

1. Open the application and load a video into the editor.
2. Locate the "How trimming works" button (Help icon) in the toolbar above the timeline, next to the aspect ratio selector.
3. Click the button to open the help dialog.
4. Verify that the dialog explains that red regions are removed.
5. Check that the visual diagram correctly illustrates the "before" and "after" states of a trim operation.
6. Verify that the close button is visible and functional.

Checklist

• I have performed a self-review of my code.
• I have added any necessary screenshots or videos.
• I have linked related issue(s) and updated the changelog if applicable.

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