Add failed campaign refund automation

[Codekill33]

Summary

• Added Shade campaign state, pledge tracking, finalization, and failed-campaign refund logic.
• Added individual refund claims and resumable batch refund processing.
• Added detailed campaign lifecycle/refund events for indexing.
• Exposed campaign APIs through ShadeTrait.
• Added focused campaign refund tests.

Verification

• cargo build -p shade passes.
• Full/filtered cargo test -p shade is blocked by pre-existing unrelated test/module compile issues in the repo.

closes #327

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