Add Subscription Count View

[Abd-Standard]

Description
Expose the total number of active subscribers for each notification channel.

Acceptance Criteria
Count updates correctly.
Read-only function is available.
Tests verify accuracy.

[BigGoodness]

Hi! I'm a full-stack developer with experience in backend (Go, Java, SQL, REST APIs) and frontend (JavaScript/TypeScript, React). I'd like to take on this issue. I'll review the existing implementation, develop a clean and maintainable solution, verify it through testing, and submit a well-documented PR that follows the project's contribution guidelines.

[OgbuKingsley166]

@OgbuKingsley166 has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Hi maintainer please assign me

ℹ️ Repo Maintainers: To accept this application, review their application or assign @OgbuKingsley166 to this issue.

[king-aj-the-first]

@king-aj-the-first has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Helloo Repo Maintainer, I'd like to work on this issue

ℹ️ Repo Maintainers: To accept this application, review their application or assign @king-aj-the-first to this issue.

[drips-wave]

Congratulations, @king-aj-the-first! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on July 30, 2026.

🧑‍💻 @king-aj-the-first: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

Warning

When opening a PR, please link it to this issue to ensure it gets tracked accurately. Points are awarded when this issue is marked as completed by the maintainer.

🤠 Repo maintainers: Please keep an eye on the contributor's progress and review their work before the due date. You can manage this issue, including adjusting its complexity and points, here.

🌊 Happy Wave 🌊