feat: implement get_active_campaign_count

[ryzen-xp]

Description

Closes #103

What

Adds get_active_campaign_count to return the number of campaigns whose deadline hasn't passed yet.

Implementation

Iterates over AllCampaigns already maintained by create_campaign. No new storage keys needed.

Tests

• Empty state returns 0
• All active campaigns counted correctly
• All expired returns 0
• Boundary: exactly at deadline vs one second before
• Count decreases as time advances
• Fully funded campaign still counts until deadline passes

Screenshots

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Checklist

• Follows existing code patterns
• No new storage keys introduced
• Tests added
• Closes [FUNCTION] implement get_active_campaign_count #103

[ryzen-xp]

hello @Akshola00 , I removed conflict chekc now

[Akshola00]

Thanks
Taking a look now

[Akshola00]

Pls fix ci issues

[ryzen-xp]

hello @Akshola00 , can you check now

[Akshola00]

Thank you for your contribution
Looks good to me