Add test: emergency withdrawal with unequal contribution states

[big14way]

Test emergency withdrawal when members have contributed different amounts across rounds.

Acceptance Criteria:

• Run 2 of 5 rounds with full contributions
• Trigger emergency withdrawal mid-round 3
• Verify proportional distribution based on actual contributions
• Verify all funds are returned (no tokens stuck in contract)

Files: contracts/sorosave/src/test.rs

[WuXieSec]

/attempt #76

I’m taking this bounty and can deliver quickly.

Plan:

1. Build unequal-contribution state across rounds in test.rs
2. Trigger emergency withdrawal during an incomplete round
3. Assert proportional distribution by actual paid-in amount
4. Assert full contract balance returns to members (no stuck funds)

Payout preference: PayPal (wuxiesec@gmail.com) after merge verification.

[WuXieSec]

Update: implemented and submitted PR for #76.

PR: #83

Delivered:

• Added unequal-contribution emergency-withdraw test (2 full rounds + partial round 3)
• Verified proportional distribution based on actual contribution history
• Verified no tokens remain stuck in contract after emergency withdraw
• Updated emergency-withdraw logic to satisfy the test and acceptance criteria

Validation:

• cargo test --package sorosave => 10 passed / 0 failed
• Test run used ephemeral Rust env and was removed afterwards

[qwldcl-del]

👋 Atlas here! Senior dev. I'll work on this.