feat: add last watched video feature

[whoisasx]

Hi @hkirat, @devsargam, @Rajankannaujiya 👋

Resolves #1897
I have resolved the concerned issue. Below is a summary of the changes:

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✅ Enhancements Implemented

1. Recently Watched Video Tracking

• Previously, there was no way to identify the last video a user watched.
• I have added a banner at the top of each course section that displays the most recently played video for the user.

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2. Week Folder State Persistence

• The app did not remember which week folder the user was exploring.
• Now, when the user returns after viewing a week's content, the same week automatically remains in focus, improving navigation and overall user experience.

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3. Improved Seed File for Better Testing

The seed file has been updated to include more realistic and complete test data.
This ensures:

• More robust and reliable testing
• Better coverage of various scenarios
• Easier validation of new features (recently watched video + week focus)

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🎥 Demo

An MP4 file has been attached below to demonstrate and compare the behavior before and after the fix.

before.mp4

after.mp4

Checklist before requesting a review

• I have performed a self-review of my code
• I assure there is no similar/duplicate pull request regarding same issue