[Feature] Add a "minimum viable group size" warning when a pool drops below a healthy member count

[grantfox-oss]

Getting Started

1. Fork the repository: https://github.com/JointSave-org/Joint_Save
2. Clone your fork:

   git clone https://github.com/<your-username>/Joint_Save.git
   cd Joint_Save

3. Create a new branch:

   git checkout -b feat/low-member-count-warning

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Overview

With remove_member (and the upcoming self-service leave function, if that ships) now letting pools shrink over time, a Rotational pool with very few members left (e.g. down to 2) has a meaningfully different risk profile than one with many — a single missed deposit affects a much larger share of the pool. There's currently no warning surfaced to members about this.

Requirements

• Add a simple, non-blocking banner on the group detail page when a Rotational pool's member count drops to 2 or fewer: "This pool has very few members remaining — consider inviting more or planning for a shorter cycle"
• This is purely informational, not a hard restriction — don't block any pool actions because of it
• Reasonable threshold is a starting suggestion; feel free to propose a better one with reasoning in the PR

Acceptance Criteria

• Banner appears correctly when a pool's member count is at or below the threshold
• Banner doesn't appear for healthy-sized pools
• No functional restriction introduced — purely informational

[khanavi272-spec]

I would like to work on this issue

[ComputerOracle]

hello dear maintainer please assign me to this issue

[TheEammneulChinedu]

I can work on this.

[grantfox-oss]

🦊 GrantFox — @ComputerOracle 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 #150)
2. Your PR will be reviewed by the JointSave-org maintainers

Good luck! Track your progress on GrantFox.

[grantfox-oss]

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

@khanavi272-spec's PR #153 was approved and merged by @Sendi0011.

🏆 @khanavi272-spec: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (48 total points). Track your full progress on GrantFox.

👏 Great work, @khanavi272-spec! Keep contributing to JointSave-org.