Use effective raised amount for withdrawals

[Killerjunior]

📌 Description

Fixes withdraw_funds so platform fees, creator payout, reserve calculation, and global raised cleanup use campaign.effective_amount_raised instead of historical campaign.amount_raised. This prevents fees from being charged on funds that have already been refunded.

🔗 Related Issues

Fixes #514

🧪 Changes Made

• Bug fix
• New feature
• Refactor
• Documentation update

✅ Checklist

• Code compiles successfully
• Tests added/updated and passing
• Linting passes (no warnings/errors)
• Documentation updated (if required)
• No breaking changes (or clearly documented)

⚠️ Breaking Changes

None.

📸 Screenshots (if applicable)

Not applicable.

🧩 Additional Notes

Added a regression test proving withdrawal fees are calculated from live effective funds after a simulated refund. I could not run the focused tests locally because Cargo dependency resolution failed on crates.io SSL/cached dependency availability for ryu; cargo fmt --all completed successfully.

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[davidmaronio]

the intent (use the post-refund effective amount as the fee/reserve basis) is reasonable, but it doesn't compile, clippy: E0425 cannot find value withdraw_basis (withdraw.rs, x2). you reference withdraw_basis but never bind it, add let withdraw_basis = campaign.effective_amount_raised;. then run cargo fmt and rebase onto a clean main (the other compile errors in the log are from a stale base, not your diff). note #583 carries this same withdraw change plus a coverage job, so one of the two should drop it.