Implement Notification Rate Limiting

[Abd-Standard]

Description

Prevent abuse by limiting the number of notifications that can be sent within a configurable time window.

Tasks
Add rate limiter middleware.
Configure limits per user or API key.
Return informative error responses.
Record rate limit events.

Acceptance Criteria
Excess requests are blocked.
Limits are configurable.
Existing users remain unaffected below thresholds.

[jahrulezfrancis]

I would really love to implement the notification rate limiting.

I’d implement a sliding‑window rate limiter as middleware: the limit and window are configurable per user/API key, backed by Redis (with an in‑memory fallback for jobs‑disabled scenarios). Exceeding the limit returns a 429 with Retry‑After and a clear error body; each event is logged. I’ll default existing users to a generous threshold so no one is affected unless they cross it—keeping the rollout safe while preventing abuse.

[grantfox-oss]

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Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #30)
2. Your PR will be reviewed by the Core-Foundry maintainers

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[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox as part of the Official Campaign campaign!

@jahrulezfrancis's PR #108 was approved and merged by @Abd-Standard.

🏆 @jahrulezfrancis: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (83 total points). Track your full progress on GrantFox.

👏 Great work, @jahrulezfrancis! Keep contributing to Core-Foundry.