Title: Add budget overspend alert notification

[Uyoxy]

Labels: enhancement help wanted

Description

src/modules/budgets/budgets.service.ts enforces budget limits but
sends no notification when a user is approaching or exceeds their
budget. Users are unaware until they check manually.

Implementation Requirements

• Add overspend check in src/modules/budgets/budgets.service.ts
• Trigger notification via src/modules/notifications/notifications.service.ts at 80% and 100% usage
• Add unit tests in src/modules/budgets/budgets.service.spec.ts

Acceptance Criteria

• Notification sent at 80% budget usage
• Notification sent at 100% budget usage
• Notifications not duplicated on repeated checks
• Unit tests pass
• CI checks pass before PR is merged

Evidence Required

Contributors must provide ALL of the following:

• Screenshot of server running with npm run start:dev
• Screenshot showing notification triggered at 80% and 100%
• Screenshot of unit tests passing
• Screenshot of passing CI checks on the PR

Files Affected

• src/modules/budgets/budgets.service.ts (modify)
• src/modules/notifications/notifications.service.ts (modify)
• src/modules/budgets/budgets.service.spec.ts (modify)

[mimijuwonlo-commits]

hello can i handle this issue

[grantfox-oss]

🦊 GrantFox — @mimijuwonlo-commits has been assigned to this issue as part of the Official Campaign campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #74)
2. Your PR will be reviewed by the stellarspend maintainers

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[grantfox-oss]

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

@mimijuwonlo-commits's PR #107 was approved and merged by @Uyoxy.

🏆 @mimijuwonlo-commits: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (156 total points). Track your full progress on GrantFox.

👏 Great work, @mimijuwonlo-commits! Keep contributing to stellarspend.